Audi A8 Power Loss + Whistling Points to Sensor Failure

Had similar issues on a 2003 Audi A6 with the same symptoms, power loss, whistling noises, and charge sensor error codes. The charge air temperature sensor was not the root cause in my case. The main problem turned out to be a damaged wiring harness connector going to the air sensor assembly. The constant engine vibration had worn through the protective sleeve, causing intermittent connection issues. The temperature sensor readings were incorrect because of this faulty connection, triggering the engine light. While it seemed minor at first, this was actually a serious issue since incorrect temperature sensor data made the engine run rich, which could have led to catalytic converter damage if left unfixed. The repair involved replacing the entire sensor wiring harness and installing additional protective shielding. The automotive sensor connection problems often get misdiagnosed as faulty sensors. A proper diagnostic should include checking all wiring and plugs connected to the engine sensor system before replacing parts. Make sure your new mechanic thoroughly tests the electrical connections first. Consider bringing these specific symptoms to their attention: Power loss during acceleration, Whistling noise under load, Engine sensor error codes, Temperature-related warnings

Thanks for the detailed write-up on the wiring harness problem. This sounds really similar to what Im experiencing on my A8. The engine temperature fluctuation and sensor errors match perfectly. Would you remember roughly how much the repair cost was? Also curious if youve had any related issues pop up since getting it fixed? Want to get a sense of whether this is likely a permanent fix or if I should watch out for other connected problems.

Got my A8 back from the shop last week after taking your advice about checking the wiring connections first. The diagnosis was spot on, it was indeed a connection issue with the charge air temperature sensor wiring. The airflow sensor readings were off because of a loose plug connection. The total repair came to 95 Euro, which covered fixing the cable and plug connection. Much better than replacing the entire temperature sensor assembly. Since the fix, the engine power is back to normal, no more whistling sounds, and the engine temperature readings are stable. The check engine light has stayed off too. The automotive sensor is now giving correct readings, and I havent seen any related issues pop up. The mechanic did a thorough check of the surrounding wiring while they were at it, so it should be a lasting fix. Monitoring the temperature gauge regularly just to be safe, but everything looks good so far.

Thank you everyone for your help on this. After getting my car back from the mechanic, I can confirm it was exactly the wiring issue mentioned. The repair was straightforward, they found a worn connector affecting the charge air temperature sensor readings. The fix cost 180 Euro total including diagnostic time. Really glad I asked here first since they might have just replaced the entire sensor otherwise. The engine power is back to normal now, no more strange noises during acceleration, and the temperature readings are stable. Had it for about two weeks since the repair with no issues. The engine sensor system is working perfectly and the check engine light has stayed off. The mechanic did warn me to watch for any temperature fluctuation just as a precaution, but so far everything is running smoothly. Much cheaper and simpler fix than I expected. Thanks again for pointing me in the right direction with this!