[permaspooked]

I have had a 2001 Sentra SE for about four years now. Never really thought about joining a forum until recently when my car started acting with something i cant seem to fix.

I had origianlly asked what was wrong on another forum but didnt many response. One person over was helping me out. I appreciate his help but still having problems. So i figured try a B15 site. So here i am.

I hope you guys dont mind helping me. Here are my symptoms and what i did. Its gonna be long but i will try to break it up so that your eyes dont get tired. lol. THANKS!!!!

One morning while driving i noticed almost no power/acceleration, It would hesitate as the rpms climbed. More like jitter as the rpms climbed. Its fine in neutral, both idling and reving. There was always a check engine light on, Had issues getting rid of it.

After a painful drive home, I borrowed my friends scanner, Got 4 codes. p0171(system to lean) p0325(knock sensor malfunction) po733(3rd gear ratio) p0134(o2 circuit no activity). I cleared the codes. The p0325(knock sensor code came right back).

Next morning i had to painfuly drive it to work. Down the block. After getting home i ran the scanner again to see if anything new showed up, At this point my light was still off. Scanner read no codes at all. I was told to check the cat by putting my hand on the exaust to see if there was flowing exaust and that the exaust wasnt to hot, Seemed fine, Was able to keep my hand there without burning it. That is where im at.

On a side note the problem seemed to get better as it warmed up, Didnt go away but was able to get through the gears easier after warming up, Any advice would be apreciated.

I disconnected the o2 on the Manifold, Getting same problem, maybe even a little bit worse then before. Did not trigger a light.

Light finally came back on. Got three codes. A p0135(02 code) and 2 about the gear ratio. But i was told that a bad 02 doesnt cause these type of problems.

replaced the upper 02. Stalled first drive after. Has never done that prior. After restart car seemed to get alot better not 100% but alot better. Still slugish. This morning from a cold start acted as if no part was replaced and went back to old symptoms. Should i try the maf next?

So you made it to the bottom. I appreciate the read. THANKS!!!

 

[i68k]

in 2002 most sentras were change to drive-by-wire, instead of your cable driven throttle body and distributor, so you have much different stuff.

you can clean the maf, use only cnc maf cleaner, and read the instructions and follow them well.

also, you have a couple of codes, that make sense, but to be sure, make sure your battery terminals are unmoveable, and you have good bare metal ground to the fenderwall. then check your battery voltage motor on&off.

other common problems are the crank and cam sensors, one of them could be failing on you, which sounds like your symptoms, but is difficult to say. if you change them, be sure to change both, as they are same part, same install, different location.

going back to your story, if youre running lean, youre exhaust should get hot faster than normal, but this was most likely fixed by your o2 sensor replacement. you could try doing an idle relearn and see if your ecu adjusts to your new o2, as it seems your old one was getting no signal. just be sure there is no air leaks between the maf and the last o2 sensor, and make sure the connectors arent full of dirt or something.

as for your other codes, your knock sensor is very picky, but could be possible that it was triggered from a bad fuel trim (having a bad/clogged o2 causes a lot of problems!), just make sure the connect isnt dirty and make sure it has a good ground to the head/block, like its not rusted on or something.

as for your gear ratio codes, assuming your drivetrain and motor is stock/oem, you shouldnt have these, its possible one of the sensors could be dirty or failing, maybe your tranny speed sensor, just take a look at them, this is why im thinking you may have some bad crank or cam sensor signals, as the ecu is detecting the engine speed is not matching the tranny speed. maybe even a bad clutch pedal microswitch, however, if you have automatic tranny you have to consider the internals as well, maybe theyre slipping when theyre not supposed to. are you experiencing hard shifts?

 

[permaspooked]

in 2002 most sentras were change to drive-by-wire, instead of your cable driven throttle body and distributor, so you have much different stuff.

you can clean the maf, use only cnc maf cleaner, and read the instructions and follow them well.

also, you have a couple of codes, that make sense, but to be sure, make sure your battery terminals are unmoveable, and you have good bare metal ground to the fenderwall. then check your battery voltage motor on&off.

other common problems are the crank and cam sensors, one of them could be failing on you, which sounds like your symptoms, but is difficult to say. if you change them, be sure to change both, as they are same part, same install, different location.

going back to your story, if youre running lean, youre exhaust should get hot faster than normal, but this was most likely fixed by your o2 sensor replacement. you could try doing an idle relearn and see if your ecu adjusts to your new o2, as it seems your old one was getting no signal. just be sure there is no air leaks between the maf and the last o2 sensor, and make sure the connectors arent full of dirt or something.

as for your other codes, your knock sensor is very picky, but could be possible that it was triggered from a bad fuel trim (having a bad/clogged o2 causes a lot of problems!), just make sure the connect isnt dirty and make sure it has a good ground to the head/block, like its not rusted on or something.

as for your gear ratio codes, assuming your drivetrain and motor is stock/oem, you shouldnt have these, its possible one of the sensors could be dirty or failing, maybe your tranny speed sensor, just take a look at them, this is why im thinking you may have some bad crank or cam sensor signals, as the ecu is detecting the engine speed is not matching the tranny speed. maybe even a bad clutch pedal microswitch, however, if you have automatic tranny you have to consider the internals as well, maybe theyre slipping when theyre not supposed to. are you experiencing hard shifts?

Thanks for the quick response!! i really appreciate it. The car is offically complete undrivable almost no acceleration at all. Basically just bogs down and trys to stall when you try to give it gas, I tried unplugging the MAF to see if anything changes, Unplugging MAF causes the car to stall instantly.

I brought home a fuel guage to check the fuel but the one i had was for cars with the nipple port, Apparently mine has to be Ted in somewhere. I checked the battery terminals they where clean and tight, replaced battery 6 months ago. retightened just incase. It is an automatic. No hard shifts, I do get delayed shifts sometimes that require letting off the gas to shift. Where can i find out how to do an idle relearn? Thanks again for reading my wall of sentences. lol.

 

[permaspooked]

Also on the fuel rail on the right side, Wich line is fuel coming in? I want to test the fuel preasure. I already plan on checking back preasure of the exaust to check my cats as well. Cant hurt to do these tests.

 

[permaspooked]

Update: i test the cats. They are ok. I tested every fuses. They are ok. P0135 and p0134 came back. I now have a p0100 but im thinking that showed up yesterday when i unplugged the maf. Car now stutters likes its gonna stall on cold start but corrects itself after. Car completely undrivable and wouldnt pass 2k wjen it was drivable. Heres a link to some live data https://www.youtube.com/watch?v=SPlr69rXynE&feature=youtube_gdata_player

 

[permaspooked]

I forgot to mention the belt squeeks as well when car is started at cold, then goes away after a minute.

 

[i68k]

you are correct, you have to T the fuel line.

when unplugging your maf, and it stalls, try this a few times, usually the first time it always stalls or stumbles really low. dont forget to clean it using only cnc maf cleaner.

you can find your idle relearn procedure in the fsm, its a free download and very useful to diagnose problems with your car. the idle relearn is very similar to the pedal dance. also you should find your answer about which side of the fuel rail to use, the qr25 are returnless so i dont want to tell you wrong. you can do the realearn again after you fix your o2 codes.

as for your automatic shifting problems, its hard to say whether it has internal problems or it is because the motor is not acting normally. have you given it a fluid flush lately? there are specific fluids to use, there is a thread around here on which fluids are compatible, im not completely familiar with automatics, but given your o2 codes, i would address those first and do research on how to change your auto tranny fluid.

as for the exhaust, it shouldnt matter, as long as theres unrestricted flow, like your cats internals dont break and lodge itself to restrict the flow, normally as long as there is good exhaust flow out the muffler, you should be ok. also wide open is good, as many people run straight pipes without any problems.

your belt may need to be replaced or tightened, just tighten it up a little if theres no cracking on your belt. if you replace, normally we recommend getting a goodyear gatorback, they are ribbed and grooved. it also seems the rubber is of better nature for weathering, but thats imo.

youre p0100 was most likely from when you unplugged your maf, and you didnt have that code before so i would disregard that one. but if you keep getting those p0135 and p0134, then theres something wrong there. youre o2 has no heater circuit, which would give the ecu skewed readings until the o2 heated up from exhaust temp, as the o2 should heat itself when the motor is cold. i dont remember if you have 2 o2 sensors, or if you have 4 of them, but your codes are for sensor1 bank1, are you sure you changed the correct o2 sensor? this should be one of your primaries, which usually controls your afr. if you only have one primary, assuming your new o2 sensor is good, youll need to check your harness/connector. make sure its not dirty or something, make sure it clicks into place! otherwise, follow the fsm, it show what voltages youre supposed to get at the connector, as it seems there is definately something wrong with that o2, or the connection/wiring to that o2 sensor.

EDIT: hopefully you didnt use a bosch o2 sensor, if you did, get an ntk or denso and get rid of the bosch as they commonly cause more problems, your car is japanese/mexican in nature, not european. make sure it comes with a connector for the easy install, so you dont have to solder anything.

EDIT2: sorry for editting, many typos and double checking myself

 

[permaspooked]

you are correct, you have to T the fuel line.

when unplugging your maf, and it stalls, try this a few times, usually the first time it always stalls or stumbles really low. dont forget to clean it using only cnc maf cleaner.

you can find your idle relearn procedure in the fsm, its a free download and very useful to diagnose problems with your car. the idle relearn is very similar to the pedal dance. also you should find your answer about which side of the fuel rail to use, the qr25 are returnless so i dont want to tell you wrong. you can do the realearn again after you fix your o2 codes.

as for your automatic shifting problems, its hard to say whether it has internal problems or it is because the motor is not acting normally. have you given it a fluid flush lately? there are specific fluids to use, there is a thread around here on which fluids are compatible, im not completely familiar with automatics, but given your o2 codes, i would address those first and do research on how to change your auto tranny fluid.

as for the exhaust, it shouldnt matter, as long as theres unrestricted flow, like your cats internals dont break and lodge itself to restrict the flow, normally as long as there is good exhaust flow out the muffler, you should be ok. also wide open is good, as many people run straight pipes without any problems.

EDIT: The 02 brand is Denso.
EDIT: The 02 brand is Denso.
your belt may need to be replaced or tightened, just tighten it up a little if theres no cracking on your belt. if you replace, normally we recommend getting a goodyear gatorback, they are ribbed and grooved. it also seems the rubber is of better nature for weathering, but thats imo.

youre p0100 was most likely from when you unplugged your maf, but if you keep getting those p0135 and p0134, then theres something wrong there. youre o2 has no heater circuit, which would give the ecu skewed readings until the o2 heated up from exhaust temp, as the o2 should heat itself when the motor is cold. i dont remember if you have 2 o2 sensors, or if you have 4 of them, but your codes are for sensor1 bank1, are you sure you changed the correct o2 sensor? this should be one of your primaries, which usually controls your afr. if you only have one primary, assuming your new o2 sensor is good, youll need to check your harness/connector. make sure its not dirty or something, make sure it clicks into place! otherwise, follow the fsm, it show what voltages youre supposed to get at the connector, as it seems there is definately something wrong with that o2, or the connection/wiring to that o2 sensor.

EDIT: hopefully you didnt use a bosch o2 sensor, if you did, get an ntk or denso and get rid of the bosch as they commonly cause more problems, your car is japanese/mexican in nature, not european. make sure it comes with a connector for the easy install, so you dont have to solder anything.

Thanks for the reply! So i should unplug the maf a couple times and document the results? I borrowed a fuel preasure guage that allows me to T off into the fuel line.

I will take a look at the fsm program when i get home. Im almost positive the shifting codes are due to the other problems, Those will be taken care of dead last if they even come back after all said and done. I have not done a tranny service to this vehicle. It was purchased second hand and was not sure of previous services. I was told that if you dont due tranny service regualrly dont do it at all.

Alot of people where telling me its that cat. One person even sweared on it. So i did a back preasure test in the upper 02 port. All checked out ok. So there isnt enouph back preasure to cause the engine to act that way.

As far as the belt i think im gonna replace it. I will tighten it for now till i figure out where my real problem is. Cant really see a belt being the problem. Thanks for the brand suggestion i will look at those belts.

As far as the 02s are concerned i will change them all if i have to. Almost positive there are only 2. I changed the one before that cat. I was told thats what b1s1 was. the connector looked clean no problems. I put in a OEM 02 it was over 100 bucks(pre wired connector and everything). Thanks again for helping me out!!!

 

[permaspooked]

I hit edit to add but it didnt work? Anyways i wanted to add that the 02 brand is Denso.

 

[i68k]

I was told that if you dont due tranny service regualrly dont do it at all.

not sure who told you that, was it your mechanic? you tranny requires lubrication just as much as the motor itself. really, im not going to make you do anything, but you should have a regular maintenance for the tranny, i believe every 30k miles. it is easy to change the fluid (like changing oil) if your drain bolts arent stuck on, but it is a little more work to flush the tranny. just be very accurate of fluid level/amount.

as for the o2, you ecu is giving multiple electrical codes for it, so either you changed the wrong primary (if you have 4 o2 sensors), or you have wiring/electrical issues there. hopefully your new o2 wasnt defective, i usually get ntk, but havent heard anything but good news from denso o2 sensors.

you should take a look at your fsm, so you can start tracking down the voltages that are supposed to be at the o2 connector, maybe one of the wires broke/frayed or came lose somewhere up the harness more. you didnt let the wire hit the cooling fans hopefully. also hope you at least have a multimeter.

you should find your fsm free around here somewhere, try these:
allsentra.com/fsm
nicoclub.com/fsm

EDIT: yes your primary o2 sensors would be before the cat, usually higher off the ground and closer to the hood. btw, when you editted, you added it to the quote you use, next time you edit goto the bottom after the text, you should see [ / quote ] at the end of my quote, then whatever you typed so you can edit

 

[i68k]

also, check your battery voltage with motor on & off, to check your charging. if your charging system is bad, it maybe shorting the o2's voltage. i know you said you check the terminals and ground to the battery already.

 

[permaspooked]

not sure who told you that, was it your mechanic? you tranny requires lubrication just as much as the motor itself. really, im not going to make you do anything, but you should have a regular maintenance for the tranny, i believe every 30k miles. it is easy to change the fluid (like changing oil) if your drain bolts arent stuck on, but it is a little more work to flush the tranny. just be very accurate of fluid level/amount.

as for the o2, you ecu is giving multiple electrical codes for it, so either you changed the wrong primary (if you have 4 o2 sensors), or you have wiring/electrical issues there. hopefully your new o2 wasnt defective, i usually get ntk, but havent heard anything but good news from denso o2 sensors.

you should take a look at your fsm, so you can start tracking down the voltages that are supposed to be at the o2 connector, maybe one of the wires broke/frayed or came lose somewhere up the harness more. you didnt let the wire hit the cooling fans hopefully. also hope you at least have a multimeter.

you should find your fsm free around here somewhere, try these:
allsentra.com/fsm
nicoclub.com/fsm

EDIT: yes your primary o2 sensors would be before the cat, usually higher off the ground and closer to the hood. btw, when you editted, you added it to the quote you use, next time you edit goto the bottom after the text, you should see [ / quote ] at the end of my quote, then whatever you typed so you can edit

No mechanic told me this, Just what i hear around. I will have to check to see if it really is only 2 02s, Im 99% sure its 2. could the 02 after cat throw b1s1 codes? I looked at the fsm PDFs for my car, Theres alot there to go through. I will take a closer look when i get home.

Thanks for the info about edit. lol

 

[i68k]

yes, there is a lot in the fsm to go through, hopefully youve found the table of contents, usually fwd.pdf.

the o2 after the cat can throw some codes for the first sensor, as the ecu is using it for doublechecking. so if your primary clogged up over time, the second o2 maybe reading 'cleaner' air at which point the ecu will determine something is wrong and could throw an o2 code for the primary, or the secondary out of range, etc. however, this is nearly impossible for your situation, you have a missing heater circuit, which is an electrical connection to the o2 sensor (or the circuit inside the o2 sensor itself is bad), and the other code signaled is an absence of connection to the sensor, so not only is there no o2 readings, theres no heater. basically, its not the ecu observing a signal being returned from the sensor itself, but the connection to the sensor or the sensor itself not returning a signal, as you have more than one electrical circuit code, its almost safe to say its not being caused by the secondary o2.

but try reading the voltages, theres usually tell tale signals at the connector. if you know the signals/power is reaching the end of the connector, you know it should be powering the sensor. so if the connector has good voltages, you know the new sensor is defective, which you can try a new one, maybe ntk (just not bosch!) and return your denso if the ntk works fine.

 

[permaspooked]

yes, there is a lot in the fsm to go through, hopefully youve found the table of contents, usually fwd.pdf.

the o2 after the cat can throw some codes for the first sensor, as the ecu is using it for doublechecking. so if your primary clogged up over time, the second o2 maybe reading 'cleaner' air at which point the ecu will determine something is wrong and could throw an o2 code for the primary, or the secondary out of range, etc. however, this is nearly impossible for your situation, you have a missing heater circuit, which is an electrical connection to the o2 sensor (or the circuit inside the o2 sensor itself is bad), and the other code signaled is an absence of connection to the sensor, so not only is there no o2 readings, theres no heater. basically, its not the ecu observing a signal being returned from the sensor itself, but the connection to the sensor or the sensor itself not returning a signal, as you have more than one electrical circuit code, its almost safe to say its not being caused by the secondary o2.

but try reading the voltages, theres usually tell tale signals at the connector. if you know the signals/power is reaching the end of the connector, you know it should be powering the sensor. so if the connector has good voltages, you know the new sensor is defective, which you can try a new one, maybe ntk (just not bosch!) and return your denso if the ntk works fine.

I dont have multimeter handy. .


After viewing more live data noticed the upper 02 voltage drops to zero when you rev. Probably explains the p0134 code . Heres a vid https://www.youtube.com/watch?v=pnrbDkxJ8zE&feature=youtube_gdata_player .

 

[i68k]

ohh, i see it now, you must have a defective o2 sensor or something else electrical going on. hopefully your charging system isnt robbing the o2 of its power, which doesnt make much sense either as usually when you rev the charging system works better.

your primary o2 should always have a higher value than the secondary. from what i saw in the video, when it drops to 0, your secondary is at .01, so the primary should be higher than .01. i would say the o2 you got is bad/defective, otherwise there is some electrical wires crossed somewhere, that cross the o2 circuit.

however, i think you can check the charging system using your obd2 scanner, maybe scroll down? i believe you can see the battery voltage in one of the menus (not sure how to use your exact scanner), as battery voltage should be on a live data screen sort of like that one. so with the motor off, you should see the battery voltage ~12v, and with the motor on, ~14v+.

 

[permaspooked]

ohh, i see it now, you must have a defective o2 sensor or something else electrical going on. hopefully your charging system isnt robbing the o2 of its power, which doesnt make much sense either as usually when you rev the charging system works better.

your primary o2 should always have a higher value than the secondary. from what i saw in the video, when it drops to 0, your secondary is at .01, so the primary should be higher than .01. i would say the o2 you got is bad/defective, otherwise there is some electrical wires crossed somewhere, that cross the o2 circuit.

however, i think you can check the charging system using your obd2 scanner, maybe scroll down? i believe you can see the battery voltage in one of the menus (not sure how to use your exact scanner), as battery voltage should be on a live data screen sort of like that one. so with the motor off, you should see the battery voltage ~12v, and with the motor on, ~14v+.

Maybe if i get the multimeter and check the voltage coming out of the 02 connector to see if theres loss of power? I will check the scanner today after work to see if it shows the battery voltage. I dont remeber seeing any. Maybe even try the old sensor again?

EDIT: I also checked the fuel preasure alll seems good.

 

[i68k]

the data youre seeing on the obd2, is usually coming from the ecu, so whatever you read at the connector should still reflect what youre seeing on your scanner, so the connector maybe good when the motor is off seeing that the o2 seems to only lose power when youre on the throttle, which is making me question charging system cutting the o2 of its power, or some other electrical wires crossing or something. the o2 should have power when the motor is on, as usually when readings drops to exact 0 (both of them!), there is no power to the sensor, or loss of connection. one thing i can say it try wiggling the wires around, maybe one of the wires has a break in it, such that when you apply throttle the motor shifts and pulls/breaks the connection somehow?

also, there is most likely a battery voltage reading somewhere in your scanner, as it is a pretty common voltage to look at, and the ecu does have inputs for this (outputs to battery and/or brake lights in gauge cluster), so it should report it to the scanner. this way you may not need a multimeter now, although it is good to have one.

you can try the old o2 sensor, but you also had both of these codes with that old sensor (p0134 + p0135), not sure how effective this will be, but you may get different results. make sure youre using a very small amount of anti-seize on the threads if theres none already on the threads, be sure not get the anti-seize on the tip of the o2 sensor!

im not entirely sure where this problem is going, outside of a bad o2 sensor itself or bad electrical, hopefully not bad ecu, you did look at the fsm for this? i dont remember much, but there is info/specs in the fsm for the o2 sensors, maybe we missed something?

 

[permaspooked]

the data youre seeing on the obd2, is usually coming from the ecu, so whatever you read at the connector should still reflect what youre seeing on your scanner, so the connector maybe good when the motor is off seeing that the o2 seems to only lose power when youre on the throttle, which is making me question charging system cutting the o2 of its power, or some other electrical wires crossing or something. the o2 should have power when the motor is on, as usually when readings drops to exact 0 (both of them!), there is no power to the sensor, or loss of connection. one thing i can say it try wiggling the wires around, maybe one of the wires has a break in it, such that when you apply throttle the motor shifts and pulls/breaks the connection somehow?

also, there is most likely a battery voltage reading somewhere in your scanner, as it is a pretty common voltage to look at, and the ecu does have inputs for this (outputs to battery and/or brake lights in gauge cluster), so it should report it to the scanner. this way you may not need a multimeter now, although it is good to have one.

you can try the old o2 sensor, but you also had both of these codes with that old sensor (p0134 + p0135), not sure how effective this will be, but you may get different results. make sure youre using a very small amount of anti-seize on the threads if theres none already on the threads, be sure not get the anti-seize on the tip of the o2 sensor!

im not entirely sure where this problem is going, outside of a bad o2 sensor itself or bad electrical, hopefully not bad ecu, you did look at the fsm for this? i dont remember much, but there is info/specs in the fsm for the o2 sensors, maybe we missed something?

I did find the fsm pages that describe the 02s and the p0134 and p0135 code.

"Component Description
NIEC0128
The heated oxygen sensor 1 (front) is placed into the exhaust
manifold. It detects the amount of oxygen in the exhaust gas compared
to the outside air. The heated oxygen sensor 1 (front) has a
closed-end tube made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions. The heated oxygen sensor 1 (front) signal is sent to the
ECM. The ECM adjusts the injection pulse duration to achieve the
ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical
change from 1V to 0V."

After that little paragraph it shows how to diagnose with a "Consult-2" Something i dont have.

EDIT: Also found this

"2. Check harness continuity between ECM terminal 62 and HO2S1 terminal 2.
Refer to “Wiring Diagram”, EC-1575.
Continuity should exist.
3. Check harness continuity between ECM terminal 62 (or HO2S1 terminal 2) and ground.
Refer to “Wiring Diagram”, EC-1575.
Continuity should not exist.
4. Also check harness for short to power."

 

[i68k]

yea thats sounds like youre in the right place, the voltages should be greater than 0, on your scanner maybe read as low as .001, but not both values 0, as too lean is destructive to the motor. how did you make out? does it all check out?

 

[permaspooked]

yea thats sounds like youre in the right place, the voltages should be greater than 0, on your scanner maybe read as low as .001, but not both values 0, as too lean is destructive to the motor. how did you make out? does it all check out?

Hey. Havent had a chance to look at it again. I was out apartment shopping. My friend is swearing that my back preasure guage is wrong and that it is the cats. So i plan on apeasing him and trying to drive the car with the 02 disconnected. lol. I havent picked up the multimeter yet or plug in the scanner. I will hopefully have a chance to do both those things this afternoon. Thanks for continuing to help and stay interested!