VW Beetle Engine Issues Point to Faulty MAF Sensor

I had almost the exact same issue with my 2017 VW Golf last winter. Have some experience working on VWs and this particular problem was quite obvious once diagnosed properly. Started with similar symptoms, noticeable performance decline, poor fuel economy, and rough idling. The check engine light came on during highway driving. Initially thought it might be something else, but the MAF sensor turned out to be the culprit. Took it to a workshop where they confirmed the faulty mass air flow sensor through diagnostic testing. The repair process was straightforward, they replaced the MAF sensor and cleaned the surrounding area. Total cost was 365€ including parts and labor. After replacement, the fuel economy improved significantly and all other issues disappeared. Before suggesting specific solutions for your Beetle, could you share: Current mileage, When was the last time you changed the air filter, Any other warning lights besides check engine, Does the problem get worse during wet weather These details would help determine if your case is similar to what I experienced. A faulty MAF sensor is common in VWs of this generation, but its best to rule out other potential causes.

Thanks for the detailed information. My Beetle just hit 104771km and had its annual service last month. The symptoms perfectly match what you described with your Golf. After reading your response, I checked the air-fuel ratio data through an OBD reader and the readings are way off. The air filter was actually replaced during the service, so that rules out a clogged filter causing sensor failure. The engine stalling happens mostly during cold starts, and Ive noticed the smoke gets worse on humid days. No other warning lights besides the check engine light. Think I will go ahead and get the MAF sensor checked based on these matching symptoms. Would you recommend getting the throttle body cleaned while they are working in that area?

Absolutely get the throttle body cleaned while they service the air intake system. After dealing with my Golf's issues, I learned its best to handle related maintenance tasks at once to prevent future problems. The cold start issues and humidity sensitivity you mention are classic symptoms of a failing MAF sensor. The air-fuel mixture readings from your OBD scanner further confirm this diagnosis. My Golf showed similar behavioral patterns before the repair. Since your air filter is new, make sure the shop checks the air intake boot for any small cracks or loose connections. In my case, they found a tiny tear that was allowing unmetered air to enter, affecting the MAF sensor readings. A thorough throttle body cleaning should cost around 85€ extra while they are already working in that area. The improvement in throttle response makes it worthwhile, especially since your symptoms indicate the engine is struggling with air-fuel management. The check engine light should clear up shortly after the repair. Monitor your fuel consumption for the next few tanks, you should notice improvement within the first 500km of driving after the fix.

Thanks for all the insight. After getting quotes from several shops, I decided to move forward with both the MAF sensor replacement and throttle body cleaning. You were right about handling related maintenance together, the total comes to 450€ which seems reasonable given the work involved. I also did more testing with the OBD reader during different weather conditions and the air-fuel readings are definitely worse on humid mornings, just like you experienced. The performance decline and poor fuel economy have gotten bad enough that I'm scheduling the repair for next week. I appreciate the tip about checking the air intake boot. I mentioned this specifically to the shop and they said they'll inspect the entire air intake system for any leaks or damage while doing the MAF sensor replacement. Hopefully this comprehensive approach will resolve all the symptoms I've been experiencing. Will update once the work is done to confirm if it fixed the stalling, smoke, and check engine light issues. Thanks again for helping me pinpoint the likely cause instead of throwing parts at the problem.