RS5 Water Sensor Issue Causing Engine Performance Drop

As someone with moderate experience working on Audis, I had a similar sensor issue with my 2019 RS4. The symptoms you describe match what I encountered, rough running and check engine light triggered by a sensor fault. The moisture sensor malfunction turned out to be caused by a damaged wiring harness connector. Water had seeped in and corroded the pins, causing intermittent sensor readings. The repair involved replacing the connector and properly sealing it. Total cost was 95 Euro for parts and labor. Before jumping to conclusions though, could you share: Current mileage, Any recent work done on the car, Specific error codes from the diagnostic scan, Whether symptoms started suddenly or gradually, If the issue happens more in wet weather A proper sensor testing procedure needs to be done to confirm if its truly a moisture sensor problem or potentially something else triggering similar symptoms. In my case, the workshop first verified the sensor readings before replacing any parts. Would be helpful to know these details to better guide you on the diagnostic path and potential fixes.

My RS5 has 116976 KM on the odometer, and the car had its last scheduled maintenance about 2 months ago. I had a local shop perform car diagnostics which pointed to the moisture sensor being the likely culprit. They ran multiple sensor testing procedures but wanted a second opinion before proceeding with repairs. The auto electronics specialist suggested this could be a widespread issue with this particular sensor. Though the exact repair costs will vary, the total parts and labor estimate is around 450 Euro for a complete sensor replacement should it be necessary. Thanks for sharing your repair experience. The symptoms do match what I am experiencing, especially the rough running and error codes. Did your workshop mention any specific testing protocols they used to verify the sensor readings?

Thanks for the additional details about your RS5. The testing protocol used in my case involved a comprehensive electrical fault analysis using advanced car diagnostics equipment. The workshop specifically tested the sensor resistance values and monitored real-time data to confirm the malfunction indicator was indeed triggered by the water sensor. At 116K km, your situation sounds nearly identical to what I experienced. While my repair was cheaper since only the connector needed replacement, a full sensor replacement at 450 Euro seems reasonable if the sensor itself has failed. The malfunction indicator in these models can be quite sensitive to sensor issues. One key difference I notice is that my problem was clearly worse in wet conditions, which helped pinpoint the water sensor as the root cause. The workshop also performed a voltage drop test across the sensor circuit to verify the electrical fault wasn't elsewhere in the system. Before authorizing the full sensor replacement, you might want to have them check: Connector integrity and pins for corrosion, Wiring continuity to the sensor, Ground connection quality, Power supply voltage at the sensor This could potentially save you money if the issue is simply a connection problem like in my case.

The diagnostic information you shared matches my situation perfectly. Since posting my initial question, I did some follow-up checks at another workshop that also confirmed the moisture sensor malfunction through voltage testing. They actually found corroded pins in the connector, similar to your case. The car diagnostics revealed the same electrical fault pattern you described. The malfunction indicator definitely seems triggered by the moisture sensor issues, and the rough running is most noticeable during damp weather. After running comprehensive sensor testing procedures, they suggested starting with the connector replacement before considering a full sensor swap. Going this route should cost closer to 100 Euro rather than the originally quoted 450 Euro. I will have them perform the repair next week and will ensure they check all the connection points you mentioned. The systematic diagnostic approach you outlined helped narrow down the actual problem and potentially saved me quite a bit on unnecessary parts replacement. The thorough sensor fault analysis really made the difference in getting to the root cause. Thanks for sharing your experience, it helped confirm I am on the right track with the diagnosis and repair plan.