SQ8's Water Sensor Causes Rough Engine Performance

Had the same water sensor malfunction on my 2018 Audi S7 with the 4.0L engine. The rough running and check engine light turned out to be a failing moisture sensor connection in the intake system. The main issue was corrosion on the sensor plug terminals, causing intermittent connection problems. The auto electronics diagnostic showed unusual misfires because the engine management system was getting incorrect readings. A thorough car sensor testing revealed the wiring harness was intact, but the connector itself needed replacement. The repair involved cleaning the sensor housing, replacing the faulty connector, and applying dielectric grease to prevent future corrosion. This is a known issue that can lead to serious engine performance problems if left unaddressed. The moisture sensor plays a critical role in the engine management system. The fix itself takes about 2 hours of labor, including testing to confirm proper operation. Important to have a shop familiar with Audi engine diagnostics handle this, as generic OBD readings might not pinpoint the exact cause. After repair, engine performance returned to normal and the malfunction indicator has stayed off. Worth getting it checked soon, as continuing to run with faulty sensor readings can affect fuel mixture and engine efficiency.

Thanks for sharing your experience with the water sensor fault. Just wondering, how much did you end up paying for the full repair? My car diagnostics appointment is scheduled for next week, so trying to get a rough estimate. Also, has everything been running smoothly since the fix, or have you noticed any other sensor-related issues popping up?

After visiting the mechanic last month, I can confirm the moisture sensor malfunction was completely resolved. The total repair cost came to 95 Euro, which covered fixing the faulty cable connection and electrical fault diagnosis. This was actually less expensive than I initially expected. The engine has been running perfectly since the repair, with no sensor issues or malfunction indicator lights appearing. The rough running completely disappeared once they fixed the connector problem. No other sensor faults have shown up, and the engine management system is working exactly as it should. The key was getting the proper diagnosis done, turned out the sensor itself was fine, just the connection was compromised. A good shop will test the entire circuit rather than just replacing parts. They used dielectric grease on the new connection, which should prevent any future sensor issues from moisture or corrosion.

Following up on my experience, I finally got the repair done at a different shop and it turned out to be a smart move. The technician found corrosion in the sensor wiring, similar to what you described. They charged 120 Euro for the complete fix, including cleaning the connectors and applying protective coating. The engine is running perfectly smooth now and the malfunction indicator has stayed off for the past 2 weeks. No more rough idling or sensor-related problems. The new shop did thorough sensor testing before and after the repair to ensure everything was working correctly. The previous shop had missed the root cause completely and wanted to replace the entire sensor unit for 400 Euro. Really glad I sought a second opinion and found someone who actually knew how to diagnose auto electronics properly. The car feels like new again and I learned a valuable lesson about finding the right technician for sensor issues.