VW Golf NOx Sensor Issues & Exhaust System Repair Fix

I dealt with a similar issue on my 2019 VW Passat Hybrid last month. I have moderate experience working on cars, mostly basic maintenance and troubleshooting. The check engine light and pollution control warnings started appearing intermittently. After scanning, it also pointed to NOx sensor failure. Initially, I was worried about an expensive sensor replacement. Took it to my regular workshop where they discovered the actual problem was much simpler, a loose connection at the NOx sensor plug. The cable had worked itself loose over time, causing intermittent sensor readings. The repair involved cleaning the connector, securing it properly, and clearing the error codes. Total repair time was about an hour and cost 95€, which was mainly labor since no parts needed replacement. The sensor itself was functioning perfectly once properly connected. Before suggesting specific fixes for your case, could you share: Which error codes your system is showing? Are there any unusual exhaust smells? Does the check engine light stay on constantly or flicker? Have you noticed any changes in fuel consumption? This information would help determine if your issue matches what I experienced or if it might be something different in the exhaust system.

Had similar check engine codes at around 135345km. Workshop recently did a full diagnostic scan which showed a failing NOx sensor affecting the air-fuel ratio and causing exhaust system issues. They first tried cleaning and recalibrating the sensor but ultimately had to replace it since the nitrogen oxide readings remained unstable. The new sensor plus labor came to 320€. They also noticed a small exhaust leak near the flange which they fixed during the same visit. After the repair, both fuel economy and pollution control readings returned to normal. What error codes are you getting specifically? This could help determine if you are facing the same sensor issue I had.

Thanks for sharing your experience. My error codes were P0130 and P0133, which are common when the NOx sensor starts acting up. These codes typically indicate issues with the air-fuel ratio monitoring system. After reading about your repair, I am convinced our issues are very similar. My VW also showed unstable nitrogen oxide readings, though my mileage was slightly lower at 128000km. The workshop initially suggested a cleaning procedure for the sensor, but like in your case, the pollution control system kept throwing errors. The exhaust leak you mentioned near the flange is particularly interesting, I am getting a similar ticking sound from that area. This could explain why my catalyst efficiency numbers are also off. Did you notice any improvement in engine performance after the repair? I am planning to book a workshop appointment soon, and your repair cost of 320€ gives me a good reference point. Did they mention anything about the catalytic converter condition during the repair? My concern is that a faulty sensor might have affected other emission system components over time.

I dealt with multiple error codes, mainly P0130 and P0133. These codes typically indicate problems with the air-fuel mixture sensing, which matched my symptoms perfectly. My local workshop pinpointed the issue to a failed NOx sensor that was impacting the entire emission system. They confirmed there was minor damage to the catalytic converter, but nothing serious enough to require replacement. The NOx sensor replacement definitely improved overall engine performance, the car runs smoother and the exhaust leak noise is completely gone. The total repair cost was 455€, including labor and parts. This covered the new sensor installation and fixing a small exhaust leak they found during inspection. Notably, they mentioned these sensor failures are somewhat common in VW hybrids around the 130000km mark. The pollution control system is now working perfectly, with stable readings across all parameters. Fuel consumption has improved by about 0.5L/100km, which is an unexpected bonus. Based on your description, it sounds like we had nearly identical issues. Glad I could share my repair experience to help others facing similar emission sensor problems.