Hello,

My CEL has been on for sometime. I scanned the codes and got the following:

P1612: NATS CHAIN OF IMMU-ECM
P0455: EVAP System Gross Leak (0.080)
P0456: EVAP System Very Small Leak (0.020)

Re: P1612: I upgraded my car's security system in 2013, and had a spare key programmed as part of the process. The security system has worked flawlessly for the past 3 years and still does. So I am not sure what the problem is. I still have a copy of the original key. How should I proceed -- use the original for a while, clear the code and see if it reappears, or have a new one re-programmed?

P0455 & P0456: From the factory manual and information available on this site, I understand these codes are related either to EVAP canister or its sensors, or some exhaust leak in the system.

There have been some exhaust leaks in the past, which I got fixed. I also just got a new gas cap from the dealer, and ready to get to work on these EVAP codes.

-- First I want to replace the gas cap. after doing so, how long should I wait to see (i.e, check the codes again) if it has any impact?

-- If the change doesn't clear the codes, then I can proceed to plan B, and attempt to get a diagnosis from the dealer (estimate is about $150). But given the age of the car and the mileage (about 190K), is it better to just go ahead and change the EVAP canister/sensor or rather pay for diagnosis of the codes?

Thanks in advance for your input.

/MN

 

Re. P1612: Yes, I would go back to the original key and see whether the problem persists, or whether it goes away.

Re. P0455, P0456: The FSM (http://boredmder.com/FSMs/Nissan/Maxima/2002/EC.pdf) p. EC-403 lists 18 possible causes for this code, all related to the Evap subsystem. Is your Evap canister/tubing/connectors rusted a lot? If so, chances are you may have to replace it, or at least some of its parts. You can follow the diagnostic procedure on p. EC-404 but you may be short of tools.

The cost of completely replacing the Evap subsystem (parts-only) is about $300 (parts from Rockauto.com, e.g. http://boredmder.com/FSMs/Nissan/Maxima/2002/EC.pdf ). Only you can decide whether paying the dealer $150 for the diagnosis is a good deal.

I would check all the hoses and piping for leaks first. If OK, I would replace the purge valve (http://www.rockauto.com/en/moreinfo....431961&jsn=344) then proceed with the more expensive parts.

 

Here's what happened to me in regards to the P1612, and i'm still good: https://maxima.org/forums/5th-genera...ce-needed.html

 

Low batt voltage can cause other serious issues, too. I jumped and drove a 4th gen with the tranny stuck in limp mode. Turns out that the TCU was freaked out by the low voltage. New battery fixed it.

 

Thanks for all your responses. Here is some update and further questions.

P0455 & P0456: Based on information here, I noticed that my gas tank nozzle was really rusted, and the after market cap was probably a bit loose. So i cleaned out the rust and replaced the cap with the OEM one, drove the car for about 30 minutes and then scanned the code. Guess what: the P0455 (the gross leak was cleared), but strangely the P0456 (minor leak) code still remained.

P1612: I used the original key for about a day. That was also cleared when I scanned.

It is kind of weird that the change of the gas cap cleared the P0455 (the gross leak), leaving the small, minor leak (P0456). What now ?

Should I be hopeful that driving around for a little longer would clear the P0456?

Thanks - MN

 

Cracked charcoal canister is pretty common.

 

No, it's not weird. You fixed the big leak. You now only have a small leak somewhere; either your fix wasn't good enough, or there is a small leak in some other place.

 

UPDATE. for the past two days, the car hasn't shown the CEL, though I am still able to scan for the P0456 code.

At any rate, I decided to drive it for the inspection today, and it passed. So I have a sticker for the next two years, during which I will try and locate the source of the leak.

Thanks for all your support - changing the gas cap, and cleaning the rust around the nozzles did really help.

best _ MN