VW Touran Exhaust Sensor Issue Draining Power & Fuel

Having dealt with a similar issue on my VW Golf 2015 gasoline model, I understand your concerns. With some experience working on VW engines, I can share my repair journey. The symptoms you describe match what I experienced, poor performance, high fuel consumption, and that dreaded check engine light. My workshop confirmed a leak in the exhaust system that was affecting multiple exhaust components, including the temperature sensor readings. The total repair came to 265€, which covered: Full diagnostic check, Emission control system inspection, Temperature sensor replacement, Fixing the exhaust leak The sensor replacement alone would not have solved the underlying issue. The leak was causing incorrect readings, making the engine run rich to compensate. Before offering more specific advice, could you share: Engine size and type, Current mileage, Any unusual sounds from the exhaust, Whether you notice any burning smell, If the problem started suddenly or gradually This information would help determine if your issue matches what I encountered and whether you might need similar repairs.

Thanks for your response. My mileage is 48148km and the last service was just 2 months ago with no issues reported. The problem started appearing gradually over the last 2 weeks. I hear no unusual sounds from the exhaust system, and there is no burning smell. The workshop initially suggested a sensor replacement without checking for exhaust leaks, which made me suspicious. Looking at my service records, no exhaust component has ever been replaced. The check engine light started flickering before staying permanently on, and the temperature fluctuation seems more noticeable during cold starts. The 265€ cost for your repair seems reasonable if it includes a proper diagnostic check. Did the workshop provide any warranty on the sensor replacement work?

Thanks for the additional details. The situation with your Touran seems different from what I encountered with my Golf, despite the similar initial symptoms. My temperature fluctuation issues were clearly linked to the exhaust leak, but your description points more toward a standalone sensor problem. The gradual onset and cold start behavior are typical signs of heat sensor degradation affecting the engine management system. The repair on my Golf came with a 12-month warranty covering both parts and labor. Given that your system shows no signs of leaks or unusual sounds, you might be looking at a simpler fix than mine. My suggestion would be to: 1. Get a detailed diagnostic report focused on sensor readings 2. Request validation of exhaust system integrity 3. If confirmed faulty, replace the sensor with an OEM part Post-repair, my fuel consumption returned to normal within 2 tank fills, and the engine management system stabilized completely. The emission control values also showed significant improvement during the next inspection. The cost for a standalone sensor replacement should be lower than what I paid since you likely wont need the extensive exhaust work I required. Consider getting a second opinion if the current workshop seems to be rushing into repairs without proper diagnostics.

I appreciate the detailed responses and suggestions. After comparing my situation with your experience, I feel more confident about pursuing the sensor replacement but will insist on a proper diagnostic check first. The fact that your repair included a warranty is reassuring. Since my exhaust system shows no obvious issues like leaks or unusual sounds, I expect the repair cost should be lower than your 265€ case. The cold start temperature fluctuation and gradual power loss really do point toward a failing heat sensor affecting the engine management system. I will follow your advice and make sure the workshop: Runs complete diagnostics, Checks the entire exhaust component setup, Uses OEM parts for any replacement, Provides warranty coverage I will update the forum once I get the diagnostic results and repair completed. The differences between your case and mine have helped me understand what questions to ask at the workshop and what to expect from the repair process.