VW Fox Exhaust Leak Causing Multiple Engine Problems

I had a very similar issue with my 2012 VW Polo with the 1.4L gasoline engine. The symptoms were nearly identical, check engine light, rough running, and exhaust issues. After some years working on my own cars, I recognized these signs but needed professional help for this one. The workshop diagnosed a faulty lambda sensor which was causing incorrect fuel mixture readings. This led to poor combustion and the exhaust issues you described. They also found the exhaust pipe had a small crack near the connection point, allowing fumes to enter the cabin. The total repair came to 375€, including parts and labor. The fix completely resolved the rough running and eliminated the exhaust smell. The check engine light hasn't returned since. To provide more specific guidance, could you share: Your engine size and type, How long the check engine light has been on, Whether the symptoms appeared gradually or suddenly, If you have access to an OBD scanner for error codes These exhaust-related problems often start small but can lead to more serious issues if left unchecked, potentially affecting your EGR valve or causing other malfunctions in the exhaust system.

Last service was at 51000km and since then the symptoms have gradually appeared. The error codes from my OBD scanner show P0171 and P0420, suggesting a lean fuel mixture and potential catalytic converter efficiency problems. The exhaust fumes are getting worse, especially during cold starts. Good point about checking the lambda sensor, will definitely have that investigated. The exhaust leak sound is most noticeable near the front of the car, which might point to a manifold issue rather than a pipe crack. The engine light started flashing intermittently about 2 weeks ago, and now stays constantly on. Speaking of costs, 375€ sounds reasonable, was hoping it would not exceed 500€ for the full repair.

Thanks for providing those error codes, they really help narrow things down. I had similar codes on my Polo before the repairs, and the P0171 was definitely related to the lambda/oxygen sensor issue I mentioned earlier. However, the P0420 code raises additional concerns about catalytic converter efficiency that I did not face in my case. This combined with your manifold area noise suggests you might be dealing with multiple issues. The constant check engine light rather than intermittent flashing does point toward a more serious problem than what I experienced. The gradual onset of symptoms and location of the exhaust leak noise hints at a potential crack in the exhaust manifold or a failing manifold gasket. In hindsight, I should have mentioned that these issues often work together, a faulty oxygen sensor can lead to improper fuel mixtures that eventually damage the catalytic converter. My initial estimate of 375€ might be optimistic for your case. If you need both the oxygen sensor and catalytic converter replaced, plus manifold repairs, you might be looking at closer to 800-1000€. The particulate filter should also be checked while they are working on the exhaust system, as these components often affect each other. Given these symptoms are getting worse during cold starts, I would prioritize getting it checked soon to prevent further damage to the exhaust system components.

Thanks for the detailed breakdown. Your experience with the Polo has been really helpful. Based on the error codes and symptoms you described, I am more convinced now that this could be more complex than initially thought. The fact that your repair bill was 375€ gave me a good reference point, but I will prepare for potentially higher costs given the catalytic converter might need replacement. The manifold area noise in my car definitely sounds different from a simple pipe crack, and the constant engine light is concerning. My next steps will be: 1. Book the workshop appointment for next week 2. Request they specifically check the manifold, oxygen sensor and catalytic converter 3. Set aside around 1000€ for potential repairs Will start documenting when the exhaust fumes are strongest to give the mechanics more info. The cold start symptoms seem to be the worst, which as you mentioned could indicate serious exhaust system issues. Hopefully catching this before winter prevents more expensive repairs down the line. Also appreciate the tip about checking the particulate filter, will add that to the list for the mechanics to inspect. Better to have everything examined while they are working on the exhaust system anyway.