kingscorpio

Hi guys

I own a 2009 Audi Q7 3.6L. My flex pipes after the catalytic converter on the exhaust broke. TO save some buck I got just the flex pipe fix from a muffler shop. The guy did a good job but now I have been getting P0420/0430 errors and the engine Light comes on after i reset it. As for performance, I have not seen any change.

Can some advise or has experience how to fix this ?

smith2010Q7

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold
Possible Causes
Leakage in Intake and/or Exhaust System
Catalyst faulty
Oxygen Sensor(s) faulty
Oxygen Sensor(s) Control faulty
Possible Solutions
Check Intake and Exhaust System for Leaks
Check Catalyst
Check Oxygen Sensor(s)
Check Oxygen Sensor(s) Control
Perform Oxygen Sensor(s) Aging Check

Q7 Catalytic Converter, Checking.pdf

cuatrokoop

I'd suspect that "repaired" flex pipe. I had a similar issue with a 1.8T A4 and had to replace the flex pipe twice to cure the issue.

kingscorpio

Hi Smith Its strange to get code for both the BANK (1 & 2) at the same time. Thanks for the input though, I bought a VAG COM cable online and am waiting for its delivery. Once I get it I will check with the Ross tech software as well.

@cuatrokoop, I agree with you but too much of a coincidence that both the flex leaking.

Does it matter if the flex pipe size varies from the original one installed.

smith2010Q7

It does matter. The computer is design by EPA regs and if it does not measure the correct volume a code will though out a it will stay on until it reads correct.

Q7 P0420.pdf

part two is on my 1st link.

kingscorpio

Also Smith I forgot to mention, I have a leak as we ll but it is at the joint in the middle where the end muffler is. The clamp joint is leaking. I dont think this can affect but good to have your input.

Also thanks for the input and the PDF. I am also thinking of getting the ECU flashed and then see what happens.

smith2010Q7

I believe that is your problem. See if you can fix the leak and reset you code.

cuatrokoop

Depending on how the system is configured (and how sensitive the sensors are), that leak may matter. Sometimes just a small crack, even a pinhole, will matter.

kingscorpio

Hi Smith after reading your comment I got hte leak fixed and i was surprised that it did fix the errors. I reset the code after the fix and My I/M Status became yes after just 30-35 km of drive. But the next day I turned my car on and let it idle for like 5 -10 min and I again had both the codes in Pending. SO i just drove it for the whole day and again checked at night and the codes were gone. Today again I checked on cold start and I again have P0430 in pending. I will check the manifold to see if there are any leaks there. Also At certain RPM I have a bit of a different sound from the Exhaust so it looks as if I still have some leak.

kingscorpio

Thanks cuatrokoop, after reading your and smiths comment I did get the leak fixed.