VW Amarok: Rough Running + Exhaust Leak Warning Signs

Recently dealt with similar symptoms on a 2014 VW Tiguan with the 2.0 TSI engine. The check engine light and rough running were caused by a failing oxygen sensor, not an exhaust leak as initially suspected. The symptoms matched exactly: strong exhaust smell, rough idle, and decreased fuel economy. The diagnostic scan revealed the rear oxygen sensor was sending incorrect readings to the ECU, causing the engine to run rich. This created excess fuel in the exhaust system, leading to that strong smell. The real concern was potential damage to the catalytic converter if left unfixed. A faulty oxygen sensor can cause permanent damage to other exhaust components over time. The repair involved replacing both oxygen sensors since they work as a pair to properly measure exhaust gases. While having it serviced, the technician also found the EGR valve needed cleaning due to carbon buildup, a common issue that can contribute to rough running. For your Amarok, recommend getting a proper diagnostic scan first. The exhaust smell could indeed point to an exhaust leak, but could also indicate sensor issues affecting the fuel mixture. These symptoms should not be ignored as they can lead to more expensive repairs if left unchecked. Would suggest having a certified shop check the entire exhaust system, oxygen sensors, and EGR operation. This type of issue needs proper diagnostic equipment to pinpoint the exact cause.

Thanks for sharing that detailed experience with the oxygen sensors. Mine turned out to be a cracked exhaust pipe right before the catalytic converter. The engine light came on because the NOx sensors were getting incorrect readings from the leak. Did you remember roughly what you paid for fixing those sensors? Any additional malfunction issues since the repair? I am trying to budget for this repair and want to make sure I address everything while its at the shop.

Happy to report that since fixing the Lambda sensor problem, the exhaust treatment malfunction warning completely disappeared. The repair cost came to 375€ which included diagnostic time and parts replacement. The technician confirmed both oxygen sensors were communicating properly with the ECU after installation. The Tiguan has been running smoothly for several months now with no check engine lights or exhaust issues. Fuel economy actually improved once the sensors were replaced. Having a properly functioning oxygen sensor is crucial since it helps maintain the right air-fuel mixture and protects the catalytic converter from damage. Your cracked exhaust pipe issue sounds more straightforward than the sensor problems I dealt with. Just make sure they check the EGR valve and surrounding components while doing the repair since exhaust leaks can sometimes mask other underlying issues.

Thanks for the input. Got my Amarok back from the shop yesterday. The total repair came to 450€ including parts and labor. They welded the cracked section of the exhaust pipe and did a full inspection of the system while it was up on the lift. The mechanic found the catalytic converter was still in good shape despite the leak, which was a relief. They also cleaned the particulate filter since it was showing early signs of clogging. No more engine light or exhaust smell now and the idle is much smoother. The shop explained that exhaust leaks near oxygen sensors often trigger malfunction codes because the sensors cant get accurate readings. Makes total sense why the engine light came on. They recommended checking the exhaust system during regular maintenance to catch any developing issues early. Really glad I got this sorted before it caused more problems. The car runs like new again. Thanks for helping me understand what I was dealing with.