occhis

Please keep us posted on the outcome, good or bad.

carlzimmerman

Hello P2404 friends,

I am happy to report I am still P2404 free (coming up on one month now and 600+ miles) after having the ECU replaced. My guess it was probably the fan in the ECU that was the cause of the issue, because of the determination that overheating was causing the fault.

On a separate and unrelated note: I would highly recommend having the carbon build up on the intake manifold cleaned if you haven't already. Mine was absolutely filthy, and the throttle response improved dramatically after having it done. Had timing chain replaced at 75K (at 99k now), so I should be good there for a while, but will have my cam tensioners checked around 130k when I get there. Also, new Pirelli tires just put on

Other good news: on AutoTrader there are a number of 2005-2006 Audi A6's with 3.2l engine that are for sale with 180K, 200k, and even 250k miles on them. (here) This also helped me rationalize my decision to stick it out for the long haul.

P2404 aside, any other critical things I need to be keeping in mind?

A6Gary

Thanks for the update. Not sure that overheating is the only problem, though. Yesterday, I successfully ran the 071 test (which has to be run when the engine is cold) and the EVAP test status was "SYSTEM OK". The DTC again triggered the "Check Engine" light after a short drive, so I cleared it. Today, I attempted to run the 071 test on the cold engine again. I could hear the LDP activated as the system was being pressurized, but the test result ended with "ABORT". Given I have checked both the J757 and J271 relays (both work and are not shorted), confirmed that the LDP works and its wiring is not shorted (based on being able to run the 071 periodically and activate the LDP via the OUTPUT TESTS), then the only item left is the ECU. On my A6, the ECU appears to be intermittent cause for this DTC. But I will continue to troubleshoot before I lay into A of A for a failing ECU (among other failed components)

You indicated that you had the timing chain replaced, but nothing about replacing the tensioners at the same time. Why weren't the tensioners replaced at the same time?

occhis

With the impending air bag recall it will be increasingly difficult to sell an affected car. I have one such car and dealer says Audi has not yet figured out a fix/repair. Audi is not going out of its way to remedy the situation, only advises not to use the passenger seat until the airbag is repaired/replaced.

ILLusive

A week in and all is happy faces while driving the car. It does seem to run better in general after the ECU replacement. Shifts are smoother, engine feels stronger on the butt dyno. I'm really hoping to never see that God forbidden CEL before selling the car in the next few years. I really think we have a strong case to present AoA about their faulty ECU's. $1700+ to fix this electrical gremlin is extremely costly.

A6Gary

Thanks for the update. I have also concluded that my ECM on my 2006 A6 Avant is defective because I can run the 070 test for the N80 valve operation and hear the LDP operate as it should during the test. But the 071 test that tests the LDP operation mostly gives a test result of "ABORT" w/ the reed closed (sometimes it does give a "SYSTEM OK" result). AFAIK, it appears that this PITA CEL only affects 2005 and 2006 model years, based on the reporting on this site and the other C6 site. If any owners of later C6 model years have experience this CEL, please post their experiences. Thanks.

ILLusive

Quick update: A month later and about 1000 miles, still NO CEL. Of course something else pops up(adaptive headlight warning)! Hopefully its just a broken/frayed wire or I have another headache on my hands!

A6Gary

Thanks for the update. So, even with the new ECM, the PITA DTC P2404 is still popping up? And what does your top tier Audi Tech who diagnosed the faulty ECM say now? After spending $1700+ to resolve this problem, you should have them refund your money. If a new ECM doesn't fix it, and the system is shown to have no leaks, then the problem must a Audi design error that requires a recall since the EVAP system is part of the emissions compliance system. Can you say "another dieselgate again"? Unbelievable!

occhis

I wonder if he meant to type "still no CEL", but not sure about that. Hope he chimes in here.

01j

I'm a shop owner trying to repair a 2007 A4 3.2 with the same issue. We replaced the purge valve, leak detection pump, and some vacation lines. CELL goes out then comes back on. The customer recently took the car to an Atlanta Audi dealer. The replaced the purge valve and LDP again! The customer came back to me looking for a solution. She spent $475 with us and $938 at the dealer for these repairs without success. The dealer said it was probably the ECU because the car "has 20 codes now". This included codes for all 4 ox sensors. The car does have a very strong gas smell, particularly after fillup. Has anyone experienced the strong smell? I'mean in Peachtree City, GA.