VW Fox Diesel Power Loss & Limp Mode Due to Throttle

Had similar issues on a 2005 VW Polo TDI with reduced engine power and check engine warnings. The throttle body was failing intermittently, causing the engine to enter limp mode. The throttle sensor was reporting incorrect air flow readings to the ECU, which then restricted power output as a safety measure. A diagnostic scan confirmed multiple throttle position sensor faults stored in the system. This required replacing the complete throttle body assembly since the electronics inside were defective. Not a quick roadside fix, the car stayed at the workshop for proper testing after installation to ensure the new throttle body was communicating correctly with the ECU. The throttle body is a critical component controlling engine air flow and power delivery. When it fails, it typically gets worse over time and can eventually prevent the car from running altogether. Would recommend getting it diagnosed and repaired soon to prevent being stranded. For VW diesels, using OEM parts is important as aftermarket sensors can sometimes cause compatibility issues with the engine management system. The repair process includes programming and adaptation of the new throttle body to work with your specific ECU.

Thanks for sharing that experience. I had nearly identical symptoms with my Fox last winter. The check engine light and sudden power loss had me worried. After getting it diagnosed, it was indeed the throttle sensor causing poor air flow and response delay. Mine would also drop into limp mode during highway driving which was pretty scary. The engine idling was really rough too before I got it fixed. Ended up needing the whole throttle body replaced to restore proper fuel efficiency and engine performance. Did you track what the total repair cost was for your Polo? Just curious how it compares. Also wondering if youve had any related issues pop up since getting it sorted? My Fox has been running great after the fix but always good to know what to watch out for.

Thanks for asking about the costs, happy to share an update. After getting the throttle valve replaced on my Polo, the total came to 265€ which covered the accelerator pedal module electronics that were causing the faulty readings. The engine idling is now perfectly smooth and the air flow sensors are reporting correct values to the ECU. No more sudden power loss or limp mode episodes since the repair. The throttle body is responding exactly as it should, quick and precise throttle response without any delays. It has been over 8 months now and everything related to the throttle sensor and engine performance has remained stable. Fuel economy is back to normal too. The investment in proper diagnosis and repair was definitely worth it to restore reliable operation. Glad to hear your Fox is also running well after the fix. Regular throttle body cleaning during maintenance can help prevent similar issues from developing again.

Thanks for the input. Finally got my Fox fixed last week. After checking around, found a shop specializing in VAG cars and the mechanic immediately spotted the throttle sensor issue during diagnostics. The air intake system needed a thorough cleaning too since dirt buildup was affecting the air flow readings. They replaced the throttle body and reprogrammed the ECU to make everything work together properly. Final bill came to 310€ including parts and labor. Car runs like new now, no more limp mode episodes or check engine lights. The throttle response is crisp and engine power is fully restored. Such a relief not having to worry about getting stranded anymore. My only regret is not addressing it sooner when the symptoms first started. Lesson learned about not ignoring warning signs when they pop up. At least now I know what to watch for if similar issues develop in the future.