Q3 Stalling + Smoke Issues Points to Faulty MAF Sensor

Had the exact same symptoms with a 2018 Audi Q5 gasoline. The mass air flow sensor failure caused the engine stalling and performance decline you described. The check engine light came on because the faulty MAF was sending incorrect air-fuel ratio data to the ECU. The smoke during acceleration and high fuel consumption match perfectly, when the MAF fails, the engine runs too rich from incorrect air measurement. The repair involved replacing the complete MAF sensor assembly since cleaning alone did not resolve the issue. This is a relatively serious problem that needs prompt attention, as continued driving can damage the catalytic converter due to improper air-fuel mixture. The good thing is MAF sensor issues are straightforward to diagnose with proper diagnostic equipment. Would suggest getting the trouble codes read first. A faulty MAF typically triggers specific codes like P0101 or P0102. Having these codes helps verify the diagnosis before any parts are replaced. Its worth noting that in some cases the symptoms can also indicate vacuum leaks or oxygen sensor issues. But based on the specific combination of stalling, smoke, and high fuel use, the MAF sensor is the likely culprit here.

Thanks for sharing your experience. That was really helpful to hear someone else had similar problems. Just had my Q3 fixed and the MAF sensor replacement resolved the engine stalling and other issues. The air-fuel ratio is back to normal and no more smoke during acceleration. One detail, just wondering what was your final repair cost? Also, have you noticed any other problems coming up since the fix? My sensor has been working fine for a few weeks now, but I am checking the air filter more regularly to prevent future issues.

Really glad to hear the MAF sensor replacement solved your issues. For my Q5, the total repair came to 365 Euro, this covered the new sensor and labor. The fix completely resolved the fuel economy problems and erratic engine behavior. The check engine light never came back after the repair, and my car has been running perfectly since. Regular air filter maintenance is definitely smart, a clean filter helps protect the MAF sensor from contamination and ensures accurate air-fuel ratio readings. Its been over a year since my repair, and I have not experienced any related problems. Just keep up with routine maintenance, particularly the air filter checks as youre doing, and the new MAF sensor should serve you well for many years.

Thanks for the input. Just wanted to close the loop on my Q3 situation. Finally took it to a mechanic who immediately recognized the symptoms. The diagnostic scan confirmed a failing MAF sensor exactly as suggested here. Total bill came to 320 Euro which seems fair after checking around. The repair took under 2 hours and made a huge difference. No more stalling, smoke issues are gone, and my fuel economy is back to normal. As a safety measure, I had them check the complete air intake system. They found the air filter was pretty dirty, so I had that replaced too. The mechanic showed me how to properly inspect it myself for future reference. Been driving for about 3 weeks now and everything runs perfectly. The check engine light has stayed off and the engine performance is solid. Definitely learned my lesson about regular air filter maintenance. Thanks again for steering me in the right direction and helping me avoid unnecessary repairs.