Audi A4 Cabrio engine indicator light comes on

Hi, I'm not a car professional, but I do have a bit of experience as I recently had a similar problem with my Audi A3 (built in 2009). My engine control unit was defective. A huge hassle, I can tell you! I took it to the garage and had it read out, where the defect was discovered. The repair ended up costing me 1000 euros. However, without precise information about your car, it's a bit difficult to give you more precise tips. Can you tell me more about your A4? More information could help me give better advice. Please also tell me the mileage and what repairs you have already done. Then I might be able to help you!

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Hi, thanks for your helpful answer. My A4 has already run 123456km. Oil change and tire change were done recently. The last service was done about 5000km ago. No major repairs so far, apart from the normal wear and tear parts. I hope this helps you to understand my problem a little better. I look forward to your advice!

(Translated from German)

Hey, thanks for the extra info! So, first, as I said, I'm not a professional, but it seems to me that you shouldn't immediately assume a faulty engine control unit. Sure, that was the case for me, but every situation is a little different. With the mileage of your A4, it could actually be the lambda sensors. The symptoms you describe are typical. You also have a petrol engine and in this case lambda sensors play an important role in efficient engine operation and fuel consumption. If they are broken, the engine gets too little or too much oxygen, which can lead to a rough engine, loss of power and increased fuel consumption. Black smoke is also a sign that something is wrong with the fuel system and the lambda sensors could be the culprit. In your case, I would really advise going to the garage and having this read out. It is difficult to determine how expensive the repair would be without an accurate diagnosis. And please check the lambda sensor heater, it could also be the reason why the lambda sensor is not working properly. Hope this helps you! Keep us up to date.

(Translated from German)

Hello, thank you for the detailed reply and the valuable tips. The issue with the lambda sensors does indeed seem very plausible and is in line with my own research. I will follow your advice and drive to the garage tomorrow to have this read out and, if necessary, initiate a repair. I didn't think so, the car has always been so reliable. Anyway, thank you for your help and I'll keep you posted! Have a nice evening!

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