What does the Volkswagen P173500 fault code mean?
2 Answers
The Volkswagen P173500 fault code indicates a malfunction in the transmission control module. It is recommended to have it inspected and repaired at a 4S shop. Symptoms of a faulty transmission control unit include abnormal transmission noise, transmission slippage, and transmission oil leakage. Transmission Abnormal Noise: Prolonged operation in high-temperature conditions can degrade the anti-wear and lubricating properties of transmission fluid, leading to wear or severe damage to components such as bearings and gears, or damage to gear side surfaces. Transmission Slippage: Excessive hydraulic oil levels can generate a large amount of air bubbles when violently agitated by planetary gears during operation. Additionally, wear or burning of clutch and brake friction plates or bands may occur. Transmission Oil Leakage: Transmission oil leakage results in insufficient internal lubrication and accelerates friction between gears, causing the transmission to malfunction. Causes of Transmission Control Unit Failure: Insufficient gear oil or poor-quality gear oil, severe wear on gear surfaces leading to excessive meshing clearance, fatigue spalling or chipping of gear teeth, excessive wear on intermediate or second shafts, or severe wear on spline shafts and internal gear splines causing excessive clearance, bent shafts or loose shaft locking components, loose bearings or damaged bearing cages, and unintended contact or rubbing of shift fork non-working parts.
I've encountered similar fault codes while driving, such as P1735, which usually indicates an issue with the transmission pressure control solenoid valve. It could be an open or short circuit, preventing the transmission from regulating control pressure properly. Volkswagen vehicles often experience these problems due to aging wiring, loose connectors, or damaged sensors, leading to jerky shifts or inability to drive normally. If not repaired promptly, the increased engine load could damage more components. I think when the warning light comes on, it's best not to push it—stop and check if the fuse box is functioning properly. If not, tow it directly to the dealership for a detailed diagnostic check. Don't skimp on small repairs only to ruin major parts. Regular transmission fluid maintenance can prevent these issues. I've tried changing it myself but found it troublesome without the right tools.
