GrandVoyager Water Sensor Issues Causing Rough Starts

Having some experience with these issues, I faced a similar sensor fault on a GrandVoyager 3.8L from 2012. The symptoms were nearly identical, check engine light, rough idling, and occasional stalling during cold starts. My water sensor malfunction indicator showed similar error codes. After initial diagnosis, the workshop found that the electrical fault was actually due to a damaged connection at the sensor plug, not the sensor itself. The wire harness had some corrosion, and the pins in the connector were loose. The repair involved cleaning the connector, repairing the wiring, and securing the connection properly. Total cost was 95€, which included diagnostic time and parts. After the fix, the engine ran smoothly again and the error codes cleared. Before suggesting specific solutions, it would help to know: Have you checked if there is visible corrosion around the sensor connections? What specific error code are you getting? Does the problem get worse in wet weather? Have you noticed any coolant loss? This could help pinpoint whether your sensor issue is similar to what I experienced or if there might be other underlying problems.

Last service was at 45000 KM. The connector issue you mentioned sounds plausible. I did notice some green residue around the sensor area. The moisture sensor acts up mostly during wet conditions, showing error code P0116. The coolant level has remained stable, and I have not noticed any leaks. The check engine light occasionally turns off by itself but returns after a cold start. A local parts supplier quoted 180€ for a new sensor, but if the wiring is the real culprit, I might save some money. Would cleaning the connector first be a sensible approach before replacing the entire sensor unit? I am concerned about potential electrical fault complications if I start poking around the wiring myself.

Thanks for the additional details. Yes, the green residue you noticed matches exactly what I found on my GrandVoyager. When I first spotted it, I was also ready to replace the entire sensor unit, but thankfully took a closer look at the connection first. The P0116 code with moisture sensitivity strongly suggests a connection issue rather than a complete sensor malfunction. In my case, cleaning the connector with electrical contact cleaner and ensuring proper connection solved the car diagnostics errors entirely. Given our shared experience with these symptoms, I recommend starting with connector maintenance: Use electrical contact cleaner, Check for loose pins in the connector, Verify the wire harness integrity near the connection point, Apply dielectric grease after cleaning to prevent future corrosion My repair held up well over time, even in wet conditions, and the malfunction indicator never returned. If cleaning doesnt resolve it, then consider the sensor replacement. But spending 180€ on a new sensor when the issue might be a simple connection problem seems unnecessary. Just ensure you disconnect the battery before working on any electrical connections to avoid creating new electrical fault codes.

The green corrosion you mentioned makes me more confident about tackling the connector issue first. Thanks for sharing your experience, it matches my situation closely. The P0116 code showing up mainly in wet weather does point toward a connection problem rather than a faulty sensor. I will try cleaning the connections as suggested before spending 180€ on a new sensor unit. The auto electronics in these models seem sensitive to corrosion issues, so using electrical contact cleaner and dielectric grease makes sense as a first step. Will disconnect the battery before starting any work on the connections to avoid triggering new error codes. If cleaning the connector and securing the wiring doesn't resolve the malfunction indicator, I can always move forward with replacing the water sensor later. For now, I will get some electrical contact cleaner and dielectric grease. Will update once I have checked the connections and tested if the car diagnostics show any improvement. Thanks for potentially saving me from an unnecessary sensor replacement.