VW Polo Warning Lights Point to Faulty Oil Sensor

As someone with moderate repair experience, I encountered nearly identical issues with my 2004 VW Golf diesel. The multiple warning lights and erratic engine temperature readings were quite similar to what you describe. After running car diagnostics, my workshop identified the root cause as a damaged wiring connection to the oil temperature sensor. The cable insulation had worn through, causing intermittent false readings and triggering various warning lights. The total repair cost was 95€, which covered the labor to locate and fix the faulty connection. The repair process was relatively quick once they pinpoited the issue. The mechanics traced the wiring harness and found where it had been rubbing against a bracket, leading to the damaged connection. They repaired the wiring and secured it properly to prevent future wear. To provide more specific guidance for your case, could you share: Which error codes are stored in your system, Whether the oil gauge readings fluctuate or remain constant, If the engine temperature warning appears at specific times, Whether you notice any actual performance issues These details would help determine if your issue matches what I experienced or if further investigation might be needed.

Last time I checked the error codes were P0196 and P0198. The oil gauge readings keep fluctuating wildly, especially after the engine warms up. The automotive sensor readings seem most erratic during highway driving. Had my last service at 122000km where they changed all fluids and checked the basic sensors. The mechanic mentioned the temperature sensor might need replacement soon but didnt consider it urgent then. The oil pressure seems normal when checking with a manual gauge, which makes me think its primarily a car sensor issue rather than an actual oil pressure problem. Would replacing just the oil temperature sensor fix all these warning lights or should I expect to replace the entire sensor assembly?

Based on my experience with my VW Golf, those error codes P0196 and P0198 point directly to engine oil temperature sensor issues, matching exactly what I dealt with. The fluctuating readings you describe are remarkably similar to what I experienced. The good news is that in my case, replacing just the oil temperature sensor resolved all the warning lights. My sensor was reading wildly inconsistent values, particularly during extended drives, causing the engine temperature readings to jump erratically. The new sensor cost around 45€, and the total repair including labor came to roughly 120€. Since your manual gauge shows normal pressure, this strongly suggests your issue is indeed sensor-related rather than a mechanical oil pressure problem. The temp sensor malfunction can trigger multiple warning lights because modern engines rely heavily on accurate temperature data for optimal performance. A few technical points from my repair: The replacement fixed both the fluctuating gauge readings and error codes, No need to replace the entire sensor assembly, The engine temperature readings returned to normal, All warning lights cleared after the repair The fact that your mechanic previously flagged the temperature sensor during service further supports this diagnosis. Given the similarity to my case, a simple sensor replacement should resolve your issues.

Thanks for sharing those additional details about the error codes and symptoms. The erratic automotive sensor behavior during highway driving seems to match what others described in similar cases. Based on the responses, especially regarding the oil temperature sensor replacement costing around 120€ total, this seems like a reasonable next step. Since my oil pressure checks out with the manual gauge, focusing on the sensor issue makes sense rather than diving into more complex repairs. I will schedule the oil temperature sensor replacement soon, especially since my mechanic already flagged it during the last service. The fluctuating engine temperature readings and multiple warning lights should clear up once the new sensor is installed. Will report back after getting it fixed to confirm if replacing just the sensor resolved all the warning lights and erratic readings. Hopefully it will be a straightforward fix like the other cases shared here.