Hi. Scootty.I have a question about my car's checking engine light was on. My Audi S5 2009's engine light was on so I got it checked at authorized Audi Service and they told me the problem was catalytic converter malfunctioning, which was recalled by Audi, so they did it for free. But later they called me saying replacement was completed but the engine light returned after technician doing road test. They diagnosed again and multiple codes came up. The most serious one was Engine Knock sensor, which they said was quite severe and was big concerns for me. They asked me to leave the car for them, waiting for further diagnosis.
I was quite dubious about additional problems detected in such a sudden, so I got the car from them today and brought it to three other mechanics to check the engine light. They all told me that the Engine- Knock Sensor was not on at all and one of them did relatively thorough check and found out the Evap Solenoid was unplugged, which was the reason of causing the engine light on again(The mechanic's point of view ) So they plug the solenoid and the engine light was off again..
I have been driving more than 40 minutes after his diagnosis and the light did not go on again.
I am not sure whether Audi shop tried to deceive me by intentionally unplugging the Solenoid and tried to make money out of this. Or does Audi has much more advanced engine check system that detects problems which other mechanics' system can not? I have attached diagnosis results from one mechanics. No results from Audi because they thought repairing was still on progress.
Could you please give me some advice from your renowned professional point of view. I really do not want to ruin my car if engine knocked off without detection. Thanks and really appreciated!