audi4k

Recent Developement, funny thing is that it happened with the sunroof not working (which I need to fix too), probably coincedence.

2341 (Blink Fault Code), VAG1551/2 Fault Code Number 00537 Oxygen Sensor Control Limit exceeded, fuel pressure too low or too high, intake or exhaust leak, defective ignition system component, intake air leak after air mass sensor, O2 sensor is faulty Symptom: CO before catalyst is below 0.3% or greater than 1.0%, Extremely lean or overly rich exhaust, Spark Plug fouling.

Engine brings out this code when idling after maybe 30sec or so, however goes away right when you tap on the gas. Idle goes between maybe 600-800rpms.

No other symptom besides that. I went and changed some vacuum hoses today and cleaned the MAF (which didnt look like it needed it). Also cleaned the ISV, which looked fine as well.

The plugs, wires, cap, rotor, has been changed around 15K-20K ago. I may pull the plugs out again to check on them (but did it 5K ago); however I did notice the red film from Octane boosters containing MMT, could it be this stuff that is causing the CEL?

The only other thing i can think of is that last week I spliced the oxygen sensor line to put in an air/fuel ratio gauge, but i did it really clean.

Any ideas or opions would be great.

audi4k

OK I put back the air/fuel ratio meter. Forgot what it was doing before the CEL came on, but when cold the A/F meter reads Stoich at startup idle and lean at idle after the engine is warmed up. What does everyone else get? Car at idle running lean seems fine to me since the car shouldnt be wasting gas.

Throughout driving, it seemed normal, running on the rich side of the meter when stepping on it.

Also no change in mpg, but I guess its too early to tell.

Black-Wolf

mine read varied at startup.. when its warm idle it bounces from lean to rich and back. if yours is not bouncing you prob have a bad o2 sensor. the reaction time is prob gone due to fouling from fuel additives.

audi4k

Black-Wolf, I was considering that. Wish i paid more attention to the 02 sensor before hand.

However it does bounce back and forth when driving as it did before i had the CEL.

But definately at idle it is sitting at the lean side. As soon as I step on the gas a little the AF meter bounces and the CEL dissappears.

Kind of sucks that the 02 sensor went bad in 10-15K, but i guess it could happen.

audi4k

Ok looks like i have an exhaust manifold leak, based on the symptoms. Will find out maybe next week, once i get a fog machine in there.

Black-Wolf

that will also cause the symtoms. g/l with it