VW Lupo Flashing CEL Points to Faulty Moisture Sensor

The moisture sensor malfunction you describe matches what happened with my 2004 VW Polo. The flashing check engine light combined with rough running typically indicates a serious issue that needs immediate attention to prevent catalyst damage. In my case, the malfunction indicator was triggered by corroded connections at the moisture sensor plug. Water had seeped into the wiring harness, causing intermittent electrical contact. Auto electronics are sensitive to moisture intrusion, and sensor testing revealed the wiring needed replacement rather than just the sensor unit itself. The repair involved: Complete diagnostic scan, Testing the sensor circuit continuity, Replacing the wiring harness section, Installing new weatherproof connectors, Verifying proper water sensor operation This was a serious repair as the faulty readings were causing incorrect fuel mixture, which could have damaged the catalytic converter if left unaddressed. The system needs proper moisture sensor data to maintain optimal engine performance and emissions control. Recommend getting this checked soon, as continuing to drive with these symptoms risks more extensive damage.

Thanks for sharing that experience with the car sensor issue. The symptoms you describe on your Polo are nearly identical to what I had on my Lupo last winter. After the electrical fault was fixed, my engine ran smooth again and the check engine light stayed off. Could you share what the total repair cost was in your case? Just curious since I paid 480€ for the complete fix on mine, wondering if that was reasonable. Also, have you had any moisture sensor or related electrical issues pop up since the repair was done?

After taking my Polo to a qualified mechanic, the water sensor malfunction was completely resolved. The repair bill came to 95€, which covered fixing a faulty cable connection at the sensor plug. This was considerably less than your repair since the issue was isolated to just the connector rather than requiring extensive electrical work. Since the repair was completed, all sensor readings have remained stable with no recurring electrical fault codes. The engine continues to run smoothly, and the check engine light has stayed off. The mechanic mentioned that proper sensor testing revealed the issue was simpler than initially feared, which helped keep costs down. The key was catching the car sensor problem early before it could cause additional system damage. Regular monitoring of any sensor issue is important, as moisture-related electrical faults can sometimes indicate broader wiring problems if left unchecked. Your 480€ repair bill suggests they likely had to replace more components or perform more extensive troubleshooting than was needed in my case.

I decided to take it to a different mechanic after reading about similar sensor issues online. The car diagnostics revealed exactly what was suspected, a failing moisture sensor causing the rough running. The mechanic found corroded wiring leading to the sensor and explained how moisture intrusion had damaged multiple connection points. The full repair included: Complete system diagnostic scan, Replacement of damaged wiring section, New moisture sensor installation, Final testing to confirm fix Total cost was 480€, which seemed high at first but made sense given the extent of electrical work needed. The malfunction indicator light cleared immediately after repair and the engine has run perfectly since then. No sensor issues have returned in the 6 months since the fix. Looking back, I am glad I switched mechanics and got it properly diagnosed. The detailed explanation of the car sensor testing and repair process helped me understand why the work was necessary to prevent more serious problems.