VW Up Check Engine: Water Sensor Causing Issues

As someone with solid experience in car repairs, I dealt with a nearly identical electrical fault on my 2015 VW High Up 1.0. The malfunction indicator symptoms you describe match exactly what I encountered. After running car diagnostics, my workshop found the root cause was a corroded wire connection to the coolant level sensor. The sensor testing revealed the component itself was fine, but the auto electronics were failing due to a damaged plug connection. The fix involved: Complete sensor testing sequence, Cleaning the connector terminals, Replacing the damaged wiring section, Resetting the electrical fault codes Total cost was 95€, mostly labor for testing and repair. The engine ran perfectly after fixing the connection, and the check engine light stayed off. Before suggesting more specific solutions, could you share: Have you noticed any coolant loss? Does the rough running improve once the engine warms up? Are there any other warning lights active? Which specific error code is stored? This additional information would help confirm if your issue matches what I experienced with the sensor wiring.

Latest service was done at 27000km about 2 months ago. The symptoms you described match my experience completely. My issue turned out to be related to both the water sensor and a failing ignition coil. The car diagnostics showed error code P0303. The rough running definitely improves after warm-up, but I noticed small coolant drops under the car each morning. My moisture sensor readings were also erratic according to the workshop team. Would be helpful to know if your car diagnostics showed the same error code. The malfunction indicator in my case started flashing intermittently before becoming constant. The total repair for me cost 320€, including parts and labor for both sensor replacement and ignition coil. Since the fix, engine performance returned to normal and all warning lights cleared.

Thanks for sharing those details about your repair experience. The P0303 code on your Up matches what I encountered, though my overall repair costs were lower since I only needed the wiring fix. The erratic moisture sensor readings combined with coolant drops definitely point to a more complex issue than what I faced. The auto electronics in these models can show similar symptoms for different root causes, which explains why your repair needed both sensor and ignition coil replacement. My malfunction indicator also started intermittent before staying constant, but I never noticed coolant leaks. The sensor fault in my case was purely electrical, while yours shows actual coolant system issues. For anyone following this thread with similar symptoms, its worth noting that the sensor testing should cover both electrical connections and physical component checks. What starts as a simple sensor fault can mask other issues like failing ignition components. Since your repair included both the moisture sensor and ignition coil, the higher 320€ cost makes sense. Have you noticed any similar symptoms returning since the complete repair?

The repair has held up perfectly for the past 3 weeks. No more coolant leaks, rough running, or warning lights. The electrical fault testing really helped identify both issues, as the car sensor problems were masking the ignition coil failure. Thanks for confirming the P0303 code match. It helps knowing others had similar auto electronics issues with their Up models. The workshop mentioned these cars can sometimes show overlapping symptoms when multiple components start failing together. For reference, the exact repair breakdown was: Water sensor unit: 85€, Ignition coil: 140€, Labor including sensor testing: 95€ The car diagnostics system now shows all sensors working within normal ranges. This thread should help others identify if theyre dealing with a simple sensor connection issue like yours or a more complex problem requiring multiple part replacements like mine.