Audi A4 Quattro Problem Report

Audi A4 Quattro Check Engine Light Due to Vacuum Leaks, Oxygen Sensor, or Catalytic Converter Fault

(57 reports)

Vacuum leaks, oxygen sensor failure, and catalytic converter efficiency faults can cause the Check Engine Light to illuminate.

I have had my check engine light on for last month. The mechanic at the shop put the computer on it and it says bank 1 lean and mis fire on pistons or something like that? The car runs fine but ideals rough. -
Vacuum leaks indicated by codes. Dealer and outside mechanics used vapor sniffers to locate a problem but found nothing. After doing my own research, I tried replacing the N80 valve and the problem was fixed. A symptom of a bad N80 valve is that when fueling up the car, the engine will hesitate when starting because of the vapor backup in the failed N80 valve. A replacement can be found for around $25 and installs fairly easy. -
Replace vacuum hoses -
catalytic converter and left side blinkers -
Check engine light on. Went to Auto Zone to get a reading and the codes read that it can be a faulty turbo, catalytic converter or an air leak. -
check engine light came on - catalytic converter insuffiency - replaced converter and check engine light has come on again after 1,300 miles with new converter. Obd has to be read again. Vehicle seems to be running okay. -
The check engine light remains on. Replaced gas cap about 2 years ago. I have worn hose, that probably is leaking air. Not sure how to affect repair myself. The problem seems to be effecting my mileage performance now. -
My Audi has all the same problems. -
Check Engine Light - Replaced Sensor, Catalytic Converters, Manifold Runners, Won't Pass CA Smog -
this problem has been an issue for 4 years and 80000 miles even audi couldn't figure it out and just reset computer and I drove to another local garage and they inspected and passed it -
No solution as of yet but my check engine light just came on today with the coolant light. The coolant has been refilled but the check engine light is still on. -
same engine light and codes read catalytic converter both sides and evap leak -
Check engine light on running rough. Smells hot. Smog code comes up when checked on computer. -
I bought the car used in 2007 and it's been on ever since. We changed the sensor and it's still on. the cluster also has a problem with displaying and we got a 'used' one and still have the same problem. The electrical system must be messed up as the car alarm would go off for no reason. It's ok now. The engine is terrific and handling is great, it loves the road even in 2014 with 144,000 mi on it. -
Check engine light has come on. P0431 warm up -
Check engine light came on, dealer says its the Catalytic Converter on the left side. Wants $2400 to fix. 2003 Audo Quattro 3.0 -
There's not too many details. We bought the car yesterday and last night the check engine light came on. Saturday night meant a quick detour to Auto Zone and the code read for the catalytic converter. We're concerned also that the 75000 mile timing belt was not changed (dealer said the service records were lost and there was now telling). Our efforts to find a solid, used and affordable car seem doomed; it's a pretty grim morning. -
Engine light stays on. Catalytic converter fault. -
Check engine light was loading due to faulty catalytic converter -
Just bought tis beutty but it looks like they modified the caylityc converter and have some codes on oxygen sensor check eng light misfire on cylinder #4 it says oxygen sensor modifyied catalyticconvrtter modifyied i have no solution yet! It only have issues on iddle and its not a big issue...i like to have some recomendations to fix it -
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