Audi A3 Oil Sensor Failure Triggers Multiple Warnings

I had a very similar issue with my 2020 Audi A4 last year. I have some experience working on cars, mainly basic maintenance, but sensor issues always require professional diagnosis. The oil temperature sensor warning started appearing intermittently at first, then became constant with multiple warning lights. The engine temperature readings were inconsistent, which made me nervous about potential damage. After taking it to the workshop, they diagnosed a faulty cable connection to the temperature sensor. The connector had corroded and wasnt making proper contact. The total repair cost was 95 Euro, which covered the diagnostic work and fixing the connection. Much better than replacing the entire sensor unit. The symptoms you describe sound identical to what I experienced. However, to provide more specific guidance, could you share: When did the warning lights first appear? Are the warnings constant or intermittent? Does the oil gauge show unusual readings? Have you noticed any changes in engine performance? This information would help determine if your car sensor issue matches what I encountered with my vehicle.

Last service completed at 95000 KM. The warning lights started appearing right after the temperature dropped significantly last week. The warnings are constant now and the oil gauge fluctuates out of nowhere between normal and critically low, even though I just had an oil change. The engine runs normally with no performance issues noticed. Based on the car diagnostics performed at my local shop, they detected multiple error codes related to the oil sensor system. They initially suggested replacing the entire oil temperature sensor unit, but given your experience with just the connector, I will ask them to inspect the wiring connections first. Makes perfect sense that a corroded connector could cause these symptoms since the engine sensor readings seem erratic rather than consistently wrong. A 95 Euro repair would be much more reasonable than the 450 Euro quote I received for a complete sensor replacement.

Thanks for the additional details about your A3. Given those symptoms and timing, it definitely mirrors my A4 experience, especially the erratic oil gauge readings without actual performance impacts. The correlation with the temperature drop is telling. Cold weather often exposes existing connection issues in car diagnostics systems, particularly with oil sensor wiring. The unusual fluctuations between normal and low readings strongly suggest a connection problem rather than a complete sensor failure. My repair lasted over a year now with no recurring issues after fixing just the connector. The oil temperature readings have remained stable since then. The fact that your engine runs normally further supports this theory, a truly faulty sensor would likely trigger more consistent error patterns. Before authorizing the full sensor replacement, definitely have them: Check all connector points for corrosion, Test the wiring continuity to the oil sensor, Verify the ground connection The 450 Euro quote seems excessive if its just a connection issue. A proper inspection of the wiring should be their first step, especially since your car diagnostics point to multiple related error codes rather than a single sensor failure.

Thanks everyone for the helpful responses. Just wanted to close the loop on my A3 oil sensor situation. Took the car to the shop today and showed them the details about checking the connections first. They found significant corrosion on the temperature sensor wiring harness connector, just as suggested. The mechanic cleaned and reseated the connection, then applied dielectric grease to prevent future issues. Total cost came to 120 Euro for diagnostics and repair, much better than the original 450 Euro quote for replacing the entire engine temperature sensor unit. All warning lights are now off and the oil gauge shows stable readings again. The car sensor system seems to be working perfectly after this simple fix. Really glad I asked about this before agreeing to the more expensive repair. Will definitely keep an eye on the connections during future maintenance, especially before winter weather hits. For anyone searching with similar issues, definitely have them check the wiring and connections before replacing sensors. The symptoms of erratic readings and multiple warnings can often be traced to connection problems rather than actual sensor failures.