SQ5 MAF Sensor Failure Causes Stalling and High Fuel Use

Had similar symptoms on my 2015 S4 last winter. The check engine light combined with poor fuel economy and stalling strongly points to MAF sensor issues. The symptoms match exactly what happens when the MAF sensor fails to properly measure the air-fuel ratio. After cleaning the MAF sensor first with specialized cleaner, problems persisted. Full replacement was necessary. The smoke during acceleration is typically caused by the engine running rich due to incorrect air flow readings. The repair involved: Testing MAF sensor signal output, Checking air filter condition, Replacing MAF sensor unit, Clearing fault codes, Testing air-fuel ratio after repair This was a serious issue requiring immediate attention, as continued driving risks damage to catalytic converters and oxygen sensors. The stalling at idle is particularly concerning as it creates unsafe driving conditions. The fix resolved all symptoms: stable idle, normal fuel consumption, no more check engine warnings, and proper acceleration without smoke. Regular air filter maintenance helps prevent premature MAF sensor failure.

Thanks for confirming my suspicions about the MAF sensor issues. Your S4 symptoms match what my SQ5 is doing perfectly. Been worried about the performance decline and those check engine warnings. Since you went through this already, mind sharing what the total repair cost was? Also curious if youve had any other issues pop up since the MAF sensor replacement? Want to budget properly and avoid any surprises at the shop. My air-fuel ratio is definitely off based on the fuel consumption, so its good to know a sensor replacement sorted things out for you. Going to get this checked out this week before it causes more problems.

Just got back from having the exact same repair done on my S4. Total bill came to 365 Euro for the Mass air flow meter replacement, and it was worth every cent. The performance decline and engine stalling issues disappeared completely after fixing the defective sensor. The fuel economy returned to normal within the first tank, and the engine runs smoothly now without any stalling at idle. No smoke issues since the repair either. The air-fuel ratio is back to factory specs, which really shows in how the car performs. Havent had a single problem since the fix three months ago. The mechanic also checked the air filter during the repair, it was clean, so that wasnt contributing to the sensor failure. No check engine warnings have returned, and the car feels as responsive as new. Make sure they test the new sensor properly after installation. A proper diagnosis and repair should resolve all your symptoms just like it did with mine. Getting it fixed promptly definitely prevents more expensive issues down the line.

Thanks everyone for the helpful replies. Finally got the repair done yesterday and wanted to share my experience. The whole ordeal was actually smoother than expected. Took the car to a certified shop that specializes in these models. They confirmed the mass air flow sensor failure through proper diagnostics. Bill came to 410 Euro total including labor and parts. The check engine light cleared up right after the repair. Did a proper test drive and the car feels completely different, no more stalling, proper acceleration, and the excessive fuel consumption is gone. They also inspected the air filter while they were at it, showed me it was pretty dirty and replaced it for good measure. The air-fuel ratio is now properly regulated and the engine runs perfectly smooth. No more smoke under acceleration either. Really glad I didnt wait any longer to get this fixed. Definitely worth every penny to have it running properly again.