VW Up Engine Light + Exhaust Leak Needs Urgent Fix

Had similar symptoms on my 2015 VW Polo TSI. The check engine light combined with rough running turned out to be a failed oxygen sensor, which was causing incorrect fuel mixture readings. The exhaust smell indicates a possible leak where the exhaust pipe connects to the catalytic converter. The oxygen sensor issue required replacing both upstream and downstream sensors since they work as a pair to monitor emissions. The repair took about 2 hours, and it was important to use OEM parts to avoid further problems. After replacement, the engine ran smoothly again and the exhaust smell disappeared. This is a serious issue that needs prompt attention since faulty sensors can damage the catalytic converter if left unfixed. The sensor malfunction causes the engine to run rich, wasting fuel and potentially damaging other components. Suggest checking for: Visible exhaust leaks around pipe connections, Diagnostic scan to confirm oxygen sensor readings, Inspection of sensor wiring and connectors, Catalytic converter condition The symptoms point to either a failed oxygen sensor or exhaust leak rather than a bad catalytic converter, but professional diagnosis is needed to be certain.

Thank you for sharing your experience. I had nearly identical issues on my VW Up last year, rough engine and exhaust leak smell. The diagnostic revealed faulty NOx sensors and a cracked exhaust pipe connection right before the particulate filter. The engine malfunction started exactly like yours. Did the repair hold up well since then? Would also help to know what the total cost was in your case. The repair quote I received initially seemed quite high, so I am curious what others paid for similar work.

Just got back to update on this. The repair definitely fixed the Exhaust treatment malfunction completely. After replacing the defective Lambda sensor, the engine runs perfectly smooth with no warning lights or rough operation. The total cost came to 375€ for parts and labor, which included a full diagnostic scan to verify all NOx sensors and EGR valve readings were back to normal. No more exhaust smell or performance issues since the repair. That price is pretty standard when using genuine VW parts. If your quote is significantly higher, it might include additional work like exhaust pipe repairs or multiple sensor replacements. A proper fix with quality parts is worth the investment to prevent recurrent issues or damage to the catalytic converter. My recommendation would be to proceed with the repair using OEM parts, especially for emissions-related components. Running with faulty sensors can lead to more expensive problems down the line.

After much consideration, I finally took my VW Up to a different repair shop last week. The mechanic diagnosed multiple issues including a cracked exhaust pipe near the catalytic converter and failing NOx sensors. The EGR valve also needed cleaning due to carbon buildup. The final repair cost was 450€, which included: New exhaust pipe section, NOx sensor replacement, EGR valve service, Full diagnostic testing The repair took one full day but the results were worth it. The engine now runs smoothly with no warning lights or exhaust smell. The shop also showed me the damaged parts and explained everything clearly, which I really appreciated after my previous bad experience. The catalytic converter thankfully was still in good condition, catching the exhaust leak early prevented any damage to it. Having a proper diagnosis and quality repair has restored my confidence in the car. No more rough running or exhaust issues since the fix.