01Pathy3.5LE Posted May 30, 2006 Share Posted May 30, 2006 Hey everyone. I had my SES light come on, took it to Advanced auto parts to run a free check and this is how it came back word for word. DTC (Codes) P0430 Catalyst Efficiency Below Threshold (Bank 2) DTC Pending (Codes) P0420 Catalyst Efficiency Below Threshold (Bank 1) :help: Can someone tell me what these codes mean? My truck is driving fine. No shakes, sputters or surges. At first I thought it may be the gas cap since there were no signs of the truck running funny. I called Nissan to see if it would be a warranty issue, currently at 98K and I have until 100K for warranty. He said they would have to run a diagnostic test, if it was a covered part-no charge, if it was not covered-79 bucks for the test plus part plus labor. Can someone help me out? I'm in no situation to throw cash at the dealer right now. Thanks!!!!! Link to comment Share on other sites More sharing options...
vengeful Posted May 30, 2006 Share Posted May 30, 2006 Hmm....I dunno those codes, but from the sounds of it, your cats aren't working properly, or your O2 sensors are seeing too much emissions. There's a couple of possibilities here with that in mind. 1.) Your cats are done for and will need replaced. 2.) Your O2 Sensors are dirty and not reading properly (unlikely because it would throw an O2 Sensor code instead.) 3.) There is a bad ground causing the O2 sensors to read funny. My suggestion to you is that you drive it for a while and see if you notice any adverse effects (poor drivability, loss of power, decrease in gas mileage, etc). If you see these, then there is a problem that needs to get fixed right away. As long as the SES light isn't flashing, it means "soon" not "immediately." Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted May 30, 2006 Author Share Posted May 30, 2006 I just had the exhaust replaced (cat back) about 1200 miles ago. Shop said cats looked good (but looks may be decieving) Could something the muffler shop did cause this to happen? The light did not come on right after I left the shop, more like 6 weeks later. I'm trying to give you the situation that led up to the ses light coming on. New exhaust, old cats. Link to comment Share on other sites More sharing options...
k9sar Posted May 30, 2006 Share Posted May 30, 2006 DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT BANK, -B2) THREE WAY CATALYST FUNCTION The ECM monitors the switching frequency ratio of heated oxygen sensors 1 (front) and 2 (rear). A warm-up three way catalyst with high oxygen storage capacity will indicate a low switching frequency of rear heated oxygen sensor. As oxygen storage capacity decreases, the rear heated oxygen sensor switching frequency will increase. When the frequency ratio of front and rear heated oxygen sensors approaches a specified limit value, the warm-up three way catalyst malfunction is diagnosed. Malfunction is detected when warm-up three way catalyst does not operate properly, warm-up three way catalyst does not have enough oxygen storage capacity. Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted May 30, 2006 Author Share Posted May 30, 2006 (edited) That is a great reply to the situation. I mean no ill will when saying this, but I have no idea what you just said means. I appologise. Are there factors leading to his problem or is it an easy fix. Again, I appreciate your help SOOOOO very much, but I have no idea what you just said. Edited May 30, 2006 by 01Pathy3.5LE Link to comment Share on other sites More sharing options...
k9sar Posted May 30, 2006 Share Posted May 30, 2006 basically... there are 2 O2 sensors, one before and one after the cat conv. If the difference between the 2 is out of whack, it says your TWC system is failing (basically, your cat). However, there are a couple of things that could cause the reading without your cat actually being bad. Exhaust leaks, timing problems, plugs, vacuum leaks etc. If I recall correctly, there is an O2 test you can run from the ECU. Link to comment Share on other sites More sharing options...
k9sar Posted May 30, 2006 Share Posted May 30, 2006 1 CHECK EXHAUST SYSTEM Visually check exhaust tubes and muffler for dent. 2 CHECK EXHAUST AIR LEAK 1. Start engine and run it at idle. 2. Listen for an exhaust air leak before the warm-up three way catalyst. 3 CHECK INTAKE AIR LEAK Listen for an intake air leak after the mass air flow sensor. 4 CHECK IGNITION TIMING then comes checking the injector voltages, spark, leaky injectors, etc. Probably nothing this bad on a pathy that's only 5 yrs old. Link to comment Share on other sites More sharing options...
94extreme Posted May 30, 2006 Share Posted May 30, 2006 (edited) Edited May 30, 2006 by mzxtreme Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted May 30, 2006 Author Share Posted May 30, 2006 Thanks for the break down. I will check to see if there are any codes relating to the O2 sensor frequency being out of whack. Also, could the MAF sensor being dirty produce an error code of this type? I see "check for leak after MAF sensor" in the list of troubleshooting ideas. I have not messed with this, but I read the write up on how to clean it. Do you think cleaning it could help in any way? Link to comment Share on other sites More sharing options...
vengeful Posted May 30, 2006 Share Posted May 30, 2006 Thanks for the break down. I will check to see if there are any codes relating to the O2 sensor frequency being out of whack. Also, could the MAF sensor being dirty produce an error code of this type? I see "check for leak after MAF sensor" in the list of troubleshooting ideas. I have not messed with this, but I read the write up on how to clean it. Do you think cleaning it could help in any way? A Dirty MAF would not cause what you're experiencing. However, if the MAF is dirty, by all means, clean it - but BE CAREFUL! It's expensive! Link to comment Share on other sites More sharing options...
5523Pathfinder Posted May 31, 2006 Share Posted May 31, 2006 (edited) I would definatly suspect the MAF. It reads how much air is going into the engine. The ECM takes in that info then watches how much oxygen is in the cats(via rear o2 sensor). If the ECM mistakes how much air is going in(ie: too much or too little), it will set rear o2 sensor codes. I usually check how much air is going by with a scan tool. Ive replaced the MAF for this problem many times on the newer 3.0 and 3.5's. Unfortunatly, they are like $500 I do believe. Remember the MAF affects both banks. Edited May 31, 2006 by 5523Pathfinder Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted May 31, 2006 Author Share Posted May 31, 2006 I noticed in the codes at the top of the post, the bottom code says DTC Pending. What does the pending mean? Does this mean it is a potential problem? Did the guy pull the reader off before it was finished testing, giving a pending reading? Please advise. Sorry, new at this stuff and trying not to get screwed by the dealer! -study- Link to comment Share on other sites More sharing options...
94extreme Posted May 31, 2006 Share Posted May 31, 2006 not sure what pending means.. it could be that he unhooked it too soon. it may be worth your time to go to a different one and have the codes read again. this is definitely a cat area thing especially the way the TSB is reading. seems something 91s are known for. this should be covered irregardless any warranty unless it is unrelated to the TSB. not sure how the MAF could effect the exhaust.. hmm anyway, look for a sticky somewhere in the garage or one of the wd21s areas, yours is basically the same. there were some pics in one of those threads at least. cleaning the MAF is defnitely worthwhile especially since it can be done in 5min. Link to comment Share on other sites More sharing options...
5523Pathfinder Posted May 31, 2006 Share Posted May 31, 2006 (edited) You can get the ecm reprogrammed for free, as per above, if you are under 80,000 miles. Gotta love warranty! The pending comment means it was checked with a generic scanner. Something has to fail twice(two trip logic) before the light will come on. Pending may mean it has only failed once. Edited May 31, 2006 by 5523Pathfinder Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted June 2, 2006 Author Share Posted June 2, 2006 (edited) Dealers!!!!! :furious: :furious: :furious: After going to the dealer, they charged me 91 bucks for a diagnosis I already knew, and they are saying the cats are bad. To the tune of $1,879.00 they can make my troubles go away. Question, where would you guys start to look for trouble. I am going to change plugs and wires...any suggestions or go with NGK's? other than that, do you think timing could be throwing codes like this? A guy at autozone said the cats need to reach 1500 degrees before they operate efficiently. He said it could be something as simple as a thermostat. I am no wrench by any means and any additional advise would be appreciated. Also, if it comes down to the cats actually being bad, any sweet suggestions on aftermarket exhaust upgrades? Edited June 2, 2006 by 01Pathy3.5LE Link to comment Share on other sites More sharing options...
5523Pathfinder Posted June 2, 2006 Share Posted June 2, 2006 Ok, easy one the dealer slamming, I work at one! You can check the cats if you want. A couple of hours removing the front pipes and you can inspect the backside of the cat material. The only way we condem cats is if they have broken material in the downpipe. You might want to question how they decided the cats were bad. If a good tech looked at your truck, he should be able to show you physically that they are bad. Your other option is to take it to a different dealer and have them check. If they find something different you might try and get your money back from the first place. I still think yoiur problem is electrical. See if you can get your ecm number from the dealer. It should be on the printout from the scan tool. Then check the TSB above to see if your ecm needs reprogramming Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted June 2, 2006 Author Share Posted June 2, 2006 (edited) Nothing personal, just venting. They said mine was already re-programed. My code ended in a 3, not sure of the total code, I have it at home. I am "working" now. :type: But he said the 3 indicated is was re-programed in the past. I did buy it used. If I pull the cats, what would a bad one look like on the inside? Also, since I do not have emission requirements in my state, can I go cat-less? (sounds sexy anyway) would this be problematic? I just want this thing to last. I have 2.5 years of payments left! Edited June 2, 2006 by 01Pathy3.5LE Link to comment Share on other sites More sharing options...
87pathy Posted June 2, 2006 Share Posted June 2, 2006 both banks, same problem same time.. that means either you have a vaccum leak, both left and right o2 sensors went bad at the same time, or you have a bad mass air flow sensor. I had the exact same problem with my Expedition. it turned out to be a vaccum leak Link to comment Share on other sites More sharing options...
k9sar Posted June 2, 2006 Share Posted June 2, 2006 but I'm sure the dealer would replace your cat and O2's if you let them. hehehe (no offense 5523 ) Link to comment Share on other sites More sharing options...
5523Pathfinder Posted June 2, 2006 Share Posted June 2, 2006 Ok, the ECM has been reprogrammed, thats good. The chance of both rear o2 sensors failing at the same time is pretty rare. Both cat converters going bad at the same time is pretty rare. It sounds like the MAF meter to me, but if the dealer wants to replace the cats, hey, let 'em. But I would definatly want to see the damaged cats if I were you. I understand its hard to listen to other people when they are not there and are not actually looking at your vehicle. I am just going on what I have seen. Link to comment Share on other sites More sharing options...
rmd0311 Posted June 2, 2006 Share Posted June 2, 2006 Yeah., I got the same thing and my ECU was re-programmed free of charge. I also recently changed my exhaust. What happens if you try and replace the cats with an after market one. Do after-market cats work well with the 01's? Link to comment Share on other sites More sharing options...
5523Pathfinder Posted June 3, 2006 Share Posted June 3, 2006 I dont think that there are aftermarket cat replacements for the 3.5L. The cats are located directly behind the exhaust manifold, they actually bolt together. I would imagine if there was a replacement, It would be talked about here. Link to comment Share on other sites More sharing options...
01Pathy3.5LE Posted June 3, 2006 Author Share Posted June 3, 2006 I'm going to clean the MAF tomorrow. The dealer reset the ses light. If the problem still exists, how long before the ses light would trip again (approx) Link to comment Share on other sites More sharing options...
k9sar Posted June 3, 2006 Share Posted June 3, 2006 if it's truely your cats, it'll prolly show up teh next time you drive her up to temp. Link to comment Share on other sites More sharing options...
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