I bought a 2000 Nissan sentra gxe about 5 years ago, ran great when I first got it but then it sat for 3 an a half years. The six months I’ve had it on the road it has been nothing but nightmares... started with the MAF sensor, mid pipe went, oil gasket and rear started leaking, one engine coil 2 months ago and the second last week and thats just the major (expensive) problems i've had. Two days after having the coil replaced I’m now getting the dreaded P0420 code and nothing I read about it online is good. The shop cleared it and told me fill up with some high octane and pray that I could burn off the smog from the misfire but after 20 miles the code is back. Anyone have any advice or experience dealing with P0420 after a misfire? Am I able to attempt to burn it off or am I just up the creek without a paddle? All the mechanic told me was if the light came back on and i wanted to pass inspection i'd have to replace the cat which I'm "looking at big bucks". With 118,000 miles on it and the money dumped into it over the last 6 months I'm not sure what to do here, am I pretty much screwed?
2000 Nissan Sentra GXE and nothing but problems (todays problem: P0420)
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I would try to burn off the stuff. High octane gas shouldnt make much difference in our cars since it was made to run on regular but I guess it wouldnt hurt to try.
If you had to replace the cat I would just buy an ebay header and have an exhaust show weld two o2 bungs past the main cat. Probably cheaper than trying to buy an oem header with the cats in it. You could also go find a junkyard and pull the stock header off (that would be fun) you just would have to make sure it had 4 o2 bungs but I also dont know if I would trust a junkyard stock header. If you're dealing with a nissan dealer I'd also ask around to some shops and see if you could get it cheaper.
Hopefully someone else can give you some more info that knows more than me about this but good luck!
If you had to replace the cat I would just buy an ebay header and have an exhaust show weld two o2 bungs past the main cat. Probably cheaper than trying to buy an oem header with the cats in it. You could also go find a junkyard and pull the stock header off (that would be fun) you just would have to make sure it had 4 o2 bungs but I also dont know if I would trust a junkyard stock header. If you're dealing with a nissan dealer I'd also ask around to some shops and see if you could get it cheaper.
Hopefully someone else can give you some more info that knows more than me about this but good luck!
in his case, the high octane may make a slight difference. it should lean out as much as possible and heat that baby up. assuming he doesnt have bad o2 sensors or readings.
i would check the rest of the exhaust for leaks, particularly around the o2 sensors. if the car sat for a long period, it may have corroded and started leaking, causing a false p0420.
there are solvents you can put in your fuel, that will also aid in cleaning the cat. if these tips fail, try clearing the code and see if it comes back. when it does, i would consider an aftermarket catless header like franzn is saying. the major problems are on the 2.5L when the cat fails, it takes the motor with it, not to say it wont happen in your case.
i would check the rest of the exhaust for leaks, particularly around the o2 sensors. if the car sat for a long period, it may have corroded and started leaking, causing a false p0420.
there are solvents you can put in your fuel, that will also aid in cleaning the cat. if these tips fail, try clearing the code and see if it comes back. when it does, i would consider an aftermarket catless header like franzn is saying. the major problems are on the 2.5L when the cat fails, it takes the motor with it, not to say it wont happen in your case.
if you do end up having the cat replaced, get it your self (rockauto.com ?). i had one shop quote me a price, and they doubled the cost of the cat, then added labor. may be hard to find a shop to do that, but why pay for the cat twice....? just my $.02 worth.
also, my 2002 sentra hates cheap gas !! if i don't use a name-brand (exxon, sunoco, etc) my SES light comes on right away. a nissan dealer who replaced the cats on my g/f's Titan ($2600) said the cheap gas has no detergents in it, that is why it is cheaper.
also, my 2002 sentra hates cheap gas !! if i don't use a name-brand (exxon, sunoco, etc) my SES light comes on right away. a nissan dealer who replaced the cats on my g/f's Titan ($2600) said the cheap gas has no detergents in it, that is why it is cheaper.
Thanks for the suggestions. I didn’t get a chance to get under my car today to look for any exhaust leaks, by the time I got out of work it was already dark. As far as name brand gas normally I use name brand gas with the exception of one gas station “quality gas” which I have used multiple times over the last 3 months and my father has used for multiple years with no problems. I did have a chance to fill my half empty tank with 93 octane and grab some fuel system cleaner from autozone. Couldn’t find any converter cleaners but I’m hoping that will raise the combustion a little to burn it clean. Also had to bribe the autozone worker with a crisp 5 dollar bill to clear the code for me because he’s “technically not allowed to do that” or something of that nature. Tonight after work I put another 65 miles on my car with the high octane but same as last night, at exactly 20 miles the SES light came back on….
Here’s the newest symptoms I noticed tonight while driving, first I noticed the rpm’s were a little higher when idling, not by much just like 75 rpms and it slightly bouncing around instead of staying steady. Plus every couple of minutes I’ll feel the rpm’s drop maybe 150 rpms then it jumps back. Also the car just seems to idling rougher and maybe even a little loud or it’s that I’m just paranoid.
Which leads me to my next question, if it’s even the cat will the P0420 code reset itself when it’s clean since it seems the car tests itself every 20 miles? I’m going to get under it tomorrow and have a look around, especially around the 02 sensors and the new mid pipe that was just put on a little more than a week ago. Debating on taking it to a different shop because I starting to think they just read the code and said the cat was dead because I doubt they troubleshot all the possibilities by 10am. I guess I just have to wait and see what tomorrow brings when I get under it. Thanks again for the suggestions.
Here’s the newest symptoms I noticed tonight while driving, first I noticed the rpm’s were a little higher when idling, not by much just like 75 rpms and it slightly bouncing around instead of staying steady. Plus every couple of minutes I’ll feel the rpm’s drop maybe 150 rpms then it jumps back. Also the car just seems to idling rougher and maybe even a little loud or it’s that I’m just paranoid.
Which leads me to my next question, if it’s even the cat will the P0420 code reset itself when it’s clean since it seems the car tests itself every 20 miles? I’m going to get under it tomorrow and have a look around, especially around the 02 sensors and the new mid pipe that was just put on a little more than a week ago. Debating on taking it to a different shop because I starting to think they just read the code and said the cat was dead because I doubt they troubleshot all the possibilities by 10am. I guess I just have to wait and see what tomorrow brings when I get under it. Thanks again for the suggestions.
you dont necessarily need good brand gas, just higer octane for you situation. while your car will run fine on regular, premium (93+) will lean it out as much as possible to help clean out the cats. you may not get any added mpg, but you will get less knocks which will lean out your afr compared to having some knocks.
fuel cleaner is not the same as a cat cleaner. a catalytic converter cleaner has different chemicals in it, which may not be safe for multiple or extended use in your vehicle.
there are ways to clear your codes, without spending money. refer to the fsm for your vehicle, i think you can just disconnect the negative battery for a while, not sure if you can do the pedal dance on your year.
if your code came back in a few miles, the cat is bad, or the o2 sensors are giving bad readings, possibly from exhaust leaks or bad sensors.
while your ses light it on, the ecu will adjust your afr, most likely richen the mixture. if the rpm goes up, the ecu probably leaned out a little causing the small surge in idle. i wouldnt be concerned about this unless its stalling, fixing your ses light should fix this problem
the p0420 will require many many cycles before it clears itself, in your case, it maybe 20 miles it checks again.
fuel cleaner is not the same as a cat cleaner. a catalytic converter cleaner has different chemicals in it, which may not be safe for multiple or extended use in your vehicle.
there are ways to clear your codes, without spending money. refer to the fsm for your vehicle, i think you can just disconnect the negative battery for a while, not sure if you can do the pedal dance on your year.
if your code came back in a few miles, the cat is bad, or the o2 sensors are giving bad readings, possibly from exhaust leaks or bad sensors.
while your ses light it on, the ecu will adjust your afr, most likely richen the mixture. if the rpm goes up, the ecu probably leaned out a little causing the small surge in idle. i wouldnt be concerned about this unless its stalling, fixing your ses light should fix this problem
the p0420 will require many many cycles before it clears itself, in your case, it maybe 20 miles it checks again.
Well I went out and bought myself a Actron OBDII CP9575 scanner today at Autozone mostly because I cannot afford to fix my car right now and the mechanic said it’s drivable but It just won’t pass inspection. Jacked my car up and looked / listened for leaks with someone blocking the tail pipe and found/heard nothing. I need my car to get to work every day and with the amount of problems I have had in the last six months I wanted to be able to check if any other codes come up since the MIL is always on now.
Here’s what it pulled up in the freeze data from the time of the code, about to research it online to see what it all means but maybe someone here might notice something I will most likely miss even through its pretty straight forward.
P0420
Eng speed(rpm) 2538
Calc Load(%) 65.5
Coolant(F) 172
ST FTRM1(%) -0.8 (I think this was a negative… can’t read my own hand writing.. wow)
LT FTRM1(%) 0.8
ST FTRM2(%) 2.3
LT FTRM2(%) 0.8
Veh Speed (MPH) 45
Fuel sys1 Clsd
Fuel sys2 Clsd
Maybe something will pop out to somebody. I’m about to start looking up what it all means and other features this reader may have to aid me in figuring this out. Who knows I could just be in denial it actually went because it’s the last thing I can afford right now
Here’s what it pulled up in the freeze data from the time of the code, about to research it online to see what it all means but maybe someone here might notice something I will most likely miss even through its pretty straight forward.
P0420
Eng speed(rpm) 2538
Calc Load(%) 65.5
Coolant(F) 172
ST FTRM1(%) -0.8 (I think this was a negative… can’t read my own hand writing.. wow)
LT FTRM1(%) 0.8
ST FTRM2(%) 2.3
LT FTRM2(%) 0.8
Veh Speed (MPH) 45
Fuel sys1 Clsd
Fuel sys2 Clsd
Maybe something will pop out to somebody. I’m about to start looking up what it all means and other features this reader may have to aid me in figuring this out. Who knows I could just be in denial it actually went because it’s the last thing I can afford right now
If that code reader you got cant clear the codes you can do this http://www.b15u.com/sentra-specific...nfo/206-obd-ii-codes-list-clearing-codes.html You dont need to pay somone at autozone to clear codes for you.
I danced with that pedal for about an hour with no luck and my frustration building to an all time high. The mechanic at the shop told me he’d clear it for me one more time for free to see if it would come back on but after that I’d be on my own. By the time I was able to get to a gas station and fill up with some high octane it had already come back on. The reader does clear codes so now at least I’m able to clear it and check if any other codes pop up that I’m not aware about. It has live time data but I’m going to have to research it a little to understand what I’m looking at. I guess I’ll just have to deal with the code until I can afford to get it fixed or attempt to replace it myself but now I don’t have to worry about another code sneaking in and hiding behind what I think is a ses light caused by the P0420. Hopefully I won’t have to deal with this for long.
Well thats good, at least now you can clear the code before you get your car inspected, unless you're county/state does emmissions testing. You should seriously look into an aftermarket header to try and get rid of the problem. Most of them are pretty cheap for our cars.
you probably shouldve bough an aftermarket header, and some foulers, and just resolved the problem. but your code readers should clear codes for you with the press of a button. an aftermarket header is <$100, the foulers are like $10 or something, just a matter of installing the header. more than likely if the code is coming back that fast, the cat is bad. with the p0420, you could potential ruin your motor, there's no ses light after the p0420 to tell you anything.
btw, i dont think your throttle body is drive-by-wire. if it is cable driven, you cant do the pedal dance like the 2002+
btw, i dont think your throttle body is drive-by-wire. if it is cable driven, you cant do the pedal dance like the 2002+
Update:
So here's what I’ve tried so far and my results...
Fuel system cleaner and a full tank of high octane: Code would come back in 30 miles instead of 20
Cataclean and another full tank of high octane: Code came back every 50 miles until tank was empty then back to every 20.
Randomly spotting a tiny bit of oil coming from here and leading me to find a crack in the elbow. Replaced the PVC elbow attached to the intake air duct for under 5 bucks: After 125 miles a p0420 code stated "pending", at 200 miles it’s still pending but no SES light yet.
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Glad I decided to start saving my money to try to start fresh with a different B15 Sentra that hasn’t had the problems mine has been giving me instead of forking out the money for a new cat. Hopefully I’ll have time soon to check for other vacuum leaks and my fuel injectors because I have a feeling they might be leaking. Maybe my precat still has some kick left in it after all???
So here's what I’ve tried so far and my results...
Fuel system cleaner and a full tank of high octane: Code would come back in 30 miles instead of 20
Cataclean and another full tank of high octane: Code came back every 50 miles until tank was empty then back to every 20.
Randomly spotting a tiny bit of oil coming from here and leading me to find a crack in the elbow. Replaced the PVC elbow attached to the intake air duct for under 5 bucks: After 125 miles a p0420 code stated "pending", at 200 miles it’s still pending but no SES light yet.
Glad I decided to start saving my money to try to start fresh with a different B15 Sentra that hasn’t had the problems mine has been giving me instead of forking out the money for a new cat. Hopefully I’ll have time soon to check for other vacuum leaks and my fuel injectors because I have a feeling they might be leaking. Maybe my precat still has some kick left in it after all???
its not a good sign that youre getting oil into your intake. oil buildup/burnoff could be whats clogging up your primary o2 sensors. id hate to see your throttle body covered in oil, but it might lube it up for you. the fact that your p0420 is still lingering around is not a good sign. vacuum leaks will give you a horrible idle, but dont normally affect o2 sensors, in your case, you could have unmetered air entering/exiting the motor. i would check your o2 sensors, its possible one of your primaries is covered/caked up with oily crap. hopefully youve checked your o2 sensors, they do control your afr.
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