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What Are the Symptoms of a Faulty MAF Sensor?

Model: (Various brands) Various
Part: MAF sensor

Video tutorial

The MAF (Mass Air Flow) sensor measures the air entering the engine, helping the ECU to adjust the fuel. When it fails, the symptoms are evident.

The most common include misfires and an irregular idle, with stuttering and vibrations. Acceleration becomes sluggish, and the engine may stall at idle.

Fuel consumption increases significantly, and the exhaust may emit black smoke (rich mixture) or a rotten egg smell (lean mixture). Knocking may occur, and sometimes the engine light illuminates with codes P0100-P0103. To diagnose it, use an OBD2 reader and check the live values: with the engine off, they should be close to zero, increasing with the revs.

A practical test: disconnect the sensor connector with the engine running; if the engine continues to run, the sensor is likely faulty. If the engine stalls, it is functioning.

Cleaning with a specific spray (Liqui Moly available on Amazon with code B00295EEBK for £17.90, free delivery) or replacement will resolve the issue.


Posted on 9 July 2026 by ScegliAuto


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by ScegliAuto

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