VW Polo Transmission Failure: Sensor or Bigger Issue?

I had very similar transmission issues with my 2005 VW Golf diesel automatic last year. Having moderate experience with transmission problems, the symptoms you describe match what I encountered, the slipping, grinding during shifts, and transmission fault warnings. The oil level in the transmission turned out to be critically low, which triggered the pressure switch to malfunction. Initially, I thought it was just the sensor, but the workshop discovered the oil level problem during diagnosis. The low oil level was causing inadequate pressure in the system, leading to those grinding noises and rough shifting. The total repair came to 365€, which covered the diagnostic work, transmission oil replacement, and a new pressure switch since the old one had been damaged by running with low oil. Before suggesting more specific advice, could you share: Current mileage on your Polo, When was the last transmission oil change, Are there any oil spots visible under the car when parked, Does the grinding noise occur at specific speeds or during all gear changes These transmission issues can cascade into bigger problems if not addressed promptly. The pressure switch often acts as an early warning system for low oil level conditions. Getting it checked soon would be wise to prevent more extensive transmission damage.

Thanks for the detailed information about the transmission fault and sensor issues. Latest service was done at 98000km about 4 months ago, where they did a routine oil change but not a transmission oil service. Since then, no oil spots under the car, but the grinding occurs mostly during shifts between 2nd and 3rd gear. The transmission warning light started flashing intermittently before staying on permanently. The transmission oil pressure readings from the diagnostic scan show inconsistent values, which seems to confirm a faulty pressure switch. The high pitch grinding noise is most noticeable during cold starts in the morning. Based on your experience, it sounds like I should get both the oil level checked and have the pressure sensor replaced rather than just focusing on the sensor alone.

You are right to consider checking both the oil level and pressure sensor. After my repair last year, I learned that transmission faults often have multiple related causes. The inconsistent pressure readings from your diagnostic scan are very similar to what I experienced before my repair. In my case, the grinding noise during cold starts was directly linked to low transmission oil pressure. Once the transmission fluid was topped up and the damaged pressure sensor replaced, the grinding completely disappeared. The transmission fault warnings also cleared up immediately. The intermittent flashing of the transmission warning light before becoming permanent matches the progression I saw with my faulty oil pressure sensor. It is a typical sign of a pressure sensor beginning to fail, especially when combined with specific gear shift issues like your 2nd to 3rd gear problem. A workshop will need to check the transmission oil level properly since these transmissions require specific temperature and testing conditions for accurate measurement. When they changed my pressure sensor, they also performed a transmission oil flush which helped resolve the shifting issues. The repair cost sounds like it will be in a similar range to what I paid, but getting it done soon could prevent more expensive transmission damage.

Thanks for sharing your repair experience. My workshop just called back with the diagnostic results. You were spot on, they found both low transmission fluid and a failing pressure sensor. The transmission oil pressure readings are still unstable even after topping up the fluid, which confirms the sensor needs replacement. They did a complete system check and fortunately found no internal transmission damage from the low fluid condition. Total repair quote is 395€ including: New transmission oil pressure sensor, Complete transmission fluid change, Diagnostic testing, Labor costs Going ahead with the full repair tomorrow morning since the symptoms match exactly what you described, especially the cold start grinding and problematic 2nd to 3rd gear shifts. Really glad I caught this before any major transmission damage occurred. The transmission warning light issue makes perfect sense now, the faulty pressure sensor was giving incorrect readings which triggered the warning system. Once the new sensor and fresh fluid are installed, the warning lights and grinding should disappear completely.