VW T-Cross NOx Sensor Failure Causing Exhaust Leaks

Had similar issues on a 2017 VW T-Roc with the nitrogen oxide sensor triggering the check engine light. The exhaust fumes turned out to be more than just a sensor problem, there was a damaged connection between the catalytic converter and the emission sensor assembly. The repair involved testing the entire exhaust system since exhaust leaks can cause false sensor readings. The main issue was a corroded wiring harness connecting to the NOx sensor. The sensor itself was functioning correctly, but the faulty connection was causing erratic readings. This is typically a moderate repair when caught early, but can become serious if ignored since bad sensor readings can lead to incorrect fuel mixture and potential catalytic converter damage. The repair required replacing the wiring harness and resealing some exhaust connections. Based on your symptoms, recommend getting the exhaust system inspected, focusing on: NOx sensor connections and wiring, Catalytic converter seal integrity, Complete emission sensor diagnostic scan, Visual inspection of exhaust components for leaks The combination of check engine light and visible fumes suggests this needs attention soon to prevent more extensive damage to emission control systems.

Thanks for sharing your T-Roc experience. Very similar to my sensor failure symptoms. Could you remember what the total repair cost was? After getting it fixed, did you experience any other pollution control issues or did the fix solve everything completely? Just want to get an idea since my local repair shop quoted quite high and I am trying to figure out if that is normal for this type of exhaust system repair.

Since getting the NOx sensor connection fixed on my T-Roc, the exhaust system has worked perfectly. The repair shop found a simple issue with a cable connection to the sensor, which was causing the erratic pollution control readings. Total cost was 95€ for fixing the faulty wiring, much less than initially expected. The check engine light disappeared right after the repair and hasnt returned. No more exhaust fumes or emission control problems in the 8 months since. Looking back, I was worried it would be a major repair, but the nitrogen oxide sensor just needed proper reconnection. This is pretty typical for sensor failure issues, sometimes the fix is straightforward when you find a qualified shop that correctly diagnoses the root cause instead of just replacing parts. My previous experiences with exhaust system repairs had been much more expensive, so I was relieved this turned out to be a simple wiring problem.

Finally took my T-Cross to a different repair shop last week after reading about your experience. They diagnosed the exact same issue, a loose connection between the NOx sensor and wiring harness. Total repair cost was 120€, which included testing the entire exhaust system and fixing the connection. The mechanic showed me where exhaust fumes were leaking due to the poor sensor connection affecting the emission control system. Much better experience than my last shop that wanted to replace the entire nitrogen oxide sensor assembly for 450€. Been driving for a few days now and everything works perfectly, no check engine light, no more fumes, and the engine runs smoother. Really glad I got a second opinion instead of paying for unnecessary sensor replacement. The simple wiring fix solved all the exhaust system problems. Thanks again for sharing your repair story. It gave me confidence to try a different shop and saved me from an expensive unnecessary repair.