VW Fox Diesel: Poor MPG and Stalling Points to MAF Sensor

Had a very similar issue with my 2007 VW Polo diesel about a year ago. As someone with basic mechanical knowledge who does regular maintenance, these symptoms immediately pointed to air-fuel ratio problems. The symptoms matched exactly: poor fuel economy, engine stalling at idle, and visible smoke. Initially tried cleaning the mass air flow sensor myself, but the performance decline continued. The air intake system was properly checked at the workshop, where they confirmed a faulty MAF sensor. Total repair cost was 365€ including diagnostics, parts, and labor. The fix completely resolved all issues, fuel consumption returned to normal, no more stalling, and the smoke disappeared. Before suggesting more specific details: What engine size does your Fox have? Have you noticed any specific patterns with the stalling (cold starts, after driving for a while)? Has anyone scanned for error codes? These details would help confirm if your issue matches what I experienced. Also worth checking if the air filter is clean and if there are any visible cracks in the intake hoses, as these can cause similar symptoms but are cheaper fixes.

Thanks for sharing your experience. My Fox recently had its 40000km service, but these issues started shortly after. I am seeing the same symptoms mainly during cold starts, but the stalling happens out of nowhere too. Got error code P0101 when scanned at a local parts store. Checked the air filter and its pretty clean since it was replaced during the last service. The intake hoses look intact with no visible damage. Will probably bite the bullet and get the MAF sensor replaced since the cleaning didnt help improve the fuel economy or resolve the engine stalling. Going to schedule a workshop visit next week and will update once I know more. Just wanted to confirm the repair cost you mentioned is in line with what I should expect.

I can definitely confirm those symptoms match exactly what I experienced with my Polo. The P0101 code is the same one I got, which specifically indicates MAF sensor issues. Getting that error after a recent service actually makes sense, as sometimes disturbing the intake system during maintenance can accelerate existing MAF sensor problems. The repair cost I mentioned (365€) seems to be pretty standard for this job. The part itself was around 220€, and labor made up the rest. Since your Fox has similar engine architecture to my Polo, the cost should be comparable. Just make sure they use OEM parts, as aftermarket MAF sensors can be hit or miss with these engines. The air-fuel ratio issues caused by a bad MAF sensor definitely explain your cold start problems and unusual stalling. The fact that cleaning didnt help and your air filter is new really points to the sensor itself being the culprit, just like in my case. Would be interested to hear how the repair goes. The performance improvement after replacement was immediately noticeable in my case, the engine ran smoother, fuel economy improved significantly, and the smoke during acceleration completely disappeared.

Thanks for following up with my repair. The P0101 code and persistent symptoms convinced me to go ahead with the MAF sensor replacement. Took it to the workshop today and the total bill came to 355€, pretty close to what you paid. Must say the difference is remarkable. The check engine light is gone, fuel economy is back to normal, and the engine runs perfectly smooth even during cold starts. No more stalling or smoke issues either. Definitely worth the investment considering how much I was wasting on extra fuel consumption. You were right about sticking with OEM parts, the mechanic explained the same thing about aftermarket sensors being unreliable. The mass air flow sensor they installed was genuine VW, which probably explains why the fix worked so well. Appreciate the detailed advice about checking the air filter and intake hoses first. Even though they werent the issue in my case, its good to know the common troubleshooting steps for future reference. Will definitely keep an eye on the air intake system during future maintenance to catch any early warning signs.