PO420?
06-23-2011, 01:56 PM
#1
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Posts: 226
PO420?
So lately my SES light has been going off and on pretty often . I have had about 2 heavy trips of like 300 miles each I just changed the oil to Mobil 1 Synthetic and it seems like if it hasnt came on since but when it did show up it showed up as the code PO420 The catalyst below threshold is it something i should worry about? It just comes and goes but for this whole week it hasnt done it. ..
06-23-2011, 02:27 PM
#3
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Join Date: Nov 2010
Location: Albert Lea, MN
Posts: 78
The P0420 code is triggered due to excess oxygen in the catalyst for bank 1....in other words, a lean condition.
This could be due to a spark plug, ignition coil, exhaust leak, vacuum leak downstream of MAF sensor, or injector......unfortunately, bank 1 is the hard side to get to.
Nearly all of these conditions would likely cause the engine to run or idle roughly.
If it were me, I'd clear the code first and wait to see if it re-appears or not before getting too worried about it....besides, you said it hasn't shown up in a while?
If the code repeats, then start checking the above items.......and chase the easy stuff first...like exhaust or vacuum leak....
This could be due to a spark plug, ignition coil, exhaust leak, vacuum leak downstream of MAF sensor, or injector......unfortunately, bank 1 is the hard side to get to.
Nearly all of these conditions would likely cause the engine to run or idle roughly.
If it were me, I'd clear the code first and wait to see if it re-appears or not before getting too worried about it....besides, you said it hasn't shown up in a while?
If the code repeats, then start checking the above items.......and chase the easy stuff first...like exhaust or vacuum leak....
06-23-2011, 02:30 PM
#4
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Join Date: Nov 2010
Location: Albert Lea, MN
Posts: 78
P2135 is related to a throttle position sensor fault.....just in case you didnt find your answer yet...
06-23-2011, 02:53 PM
#5
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Join Date: Apr 2011
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The P0420 code is triggered due to excess oxygen in the catalyst for bank 1....in other words, a lean condition.
This could be due to a spark plug, ignition coil, exhaust leak, vacuum leak downstream of MAF sensor, or injector......unfortunately, bank 1 is the hard side to get to.
Nearly all of these conditions would likely cause the engine to run or idle roughly.
If it were me, I'd clear the code first and wait to see if it re-appears or not before getting too worried about it....besides, you said it hasn't shown up in a while?
If the code repeats, then start checking the above items.......and chase the easy stuff first...like exhaust or vacuum leak....
This could be due to a spark plug, ignition coil, exhaust leak, vacuum leak downstream of MAF sensor, or injector......unfortunately, bank 1 is the hard side to get to.
Nearly all of these conditions would likely cause the engine to run or idle roughly.
If it were me, I'd clear the code first and wait to see if it re-appears or not before getting too worried about it....besides, you said it hasn't shown up in a while?
If the code repeats, then start checking the above items.......and chase the easy stuff first...like exhaust or vacuum leak....
06-23-2011, 03:07 PM
#6
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Join Date: Mar 2011
Location: NW Indiana
Posts: 16
P0420 could also mean the pre-cat is going bad. That's the code that shows up for a lot of the 2.5 altima guys that have the pre-cat break apart and get sucked back into the engine. While it is not as common with the VQ, there has been some cases. Since your's is coming and going, hopefully that's not the problem.
06-23-2011, 03:59 PM
#8
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Join Date: May 2006
Location: NorCal
Posts: 626
P0420 could also mean the pre-cat is going bad. That's the code that shows up for a lot of the 2.5 altima guys that have the pre-cat break apart and get sucked back into the engine. While it is not as common with the VQ, there has been some cases. Since your's is coming and going, hopefully that's not the problem.
06-23-2011, 04:27 PM
#9
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Join Date: Apr 2011
Posts: 226
I got that code a little after 30k miles on the car and it was exactly that, although I had other codes as well. Pre-cat failed, EGR valve stuck open, fuel pump failure, all at the same time so not sure which occurred first. Nissan said they performed an inspection of the engine for potential damage from the pre-cat failure and found none. 20k miles later my engine starts burning oil at a rate of about 1qt every oil change. 40k miles later it's burning 2qts 1k miles after an oil change and they replaced my engine. Make sure it's not your pre-cats.
06-23-2011, 04:50 PM
#10
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Join Date: Mar 2011
Location: NW Indiana
Posts: 16
Eeeh...this is kinda scary it has 40k miles but it has no warranty....will get those pre cats checked out whats there to check on these lol? I know racingline sells some I think if it is these ill go with them. IT hasnt burned oil since I did the oil change....what are some of the symptons of this kind of failure?
06-23-2011, 07:27 PM
#11
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Are the precats easy to take off?
06-23-2011, 08:35 PM
#13
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Location: NW Indiana
Posts: 16
Well, its not all that difficult, but can be time consuming, depending on how stubborn the bolts are and what kind of tools you have access to. The rear one can be a pain to get to, having to work around the subframe and rear engine mount. Basically, you have to disconnect the y-pipe, then unbolt the precats from the manifolds.
But don't let all of this scare you too bad, b/c it may not be the precats. Like 67 Lamnas said, check the easy stuff and see if the code comes back. However, it probably wouldn't be a bad idea to check out the precats too, if you have the means b/c catching that early on may save you from needing a new engine.
But don't let all of this scare you too bad, b/c it may not be the precats. Like 67 Lamnas said, check the easy stuff and see if the code comes back. However, it probably wouldn't be a bad idea to check out the precats too, if you have the means b/c catching that early on may save you from needing a new engine.
Last edited by altjt02; 06-23-2011 at 08:48 PM.
06-23-2011, 08:49 PM
#14
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Posts: 226
Well, its not all that difficult, but can be time consuming, depending on how stubborn the bolts are and what kind of tools you have access to. The rear one can be a pain to get to, having to work around the subframe and rear engine mount. Basically, you have to disconnect the y-pipe, then unbolt the precats from the manifolds.
But don't let all of this scare you too bad, b/c it may not be the precats. Like 67 Lamnas said, check the easy stuff and see if the code comes back. However, it probably wouldn't be a bad idea to check out the precats too, if you have the means b/c catching that early on may save you from needing a new engine.
But don't let all of this scare you too bad, b/c it may not be the precats. Like 67 Lamnas said, check the easy stuff and see if the code comes back. However, it probably wouldn't be a bad idea to check out the precats too, if you have the means b/c catching that early on may save you from needing a new engine.
06-24-2011, 02:22 PM
#15
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Join Date: May 2006
Location: NorCal
Posts: 626
Yeah, didn't mean to scare you, just warning you since that's what happened to me after I got that code. Just check your oil level every 500 miles and see if it's dropping. But by all means, check the little things first.
09-16-2011, 03:09 PM
#17
Join Date: Aug 2005
Posts: 18
If nothing else
I would try and get this taken care of even if it's intermittent. Mine was intermittent for awhile and I kept putting it off cause I figured my CAI and nwp spacers were making mine run a little lean. Turns out it was the precats. It's a ****ty design if you ask me, to have them so close to the manifold. Mine is burning excessive oil at this point and have the rear precat to blame. If you don't do anything else, check the precats. The front one is pretty easy to get off, the rear one is kind of pain, I would slot a full day for the job. I had my car about 16" off the ground on jackstands and this was sufficient. You'll need about 20" worth of extensions, a u joint socket adapter will be helpful, and possibly a breaker bar. As was said by another poster, not trying to scare you, but it can happen and engines are expensive. I'm just gonna see how long mine will hold out with hollowed out precats at this point.
01-22-2012, 04:19 PM
#19
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Join Date: Mar 2011
Location: IL
Posts: 43
fixes
So what fixes have people tried and worked best? seems like racingline's precats are the easiest and chepest, but will eventually have to be replaced again. Cattman headers more problem free with no cats, but require more work with the wiring and etc.
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