The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates deceleration or idle.

A large quantity of air entering the engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit and a signal circuit. The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on inlet air flow through the sensor bore. The PCM uses the barometric pressure, air density, manifold pressure, throttle position, and the engine RPM in order to calculate a predicted MAF value. The PCM compares the actual MAF sensor signal to the predicted MAF value in order to determine if the signal is stuck based on a lack of variation, or is too low or too high for a given operating condition. DTC P0101 will set if the actual MAF sensor signal is not within a predetermined range of the calculated MAF value.
Possible causes for this code are:

  • Faulty sensor
  • Broken wires at the sensor connector. Tug on each to see if it stretches or breaks
  • Loose air intake duct or breather hose / tube between the MAF sensor and the engine
  • Dirty sensor. Try spraying cleaner inside the sensor, then take for drive to "Blow out" the cleaner

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    Comments (4)

      • JIM

        I'm getting p0101 and p0131 constantly on my 2000 grand am. I seem to be lacking power sometimes, and I've had it twice now where I have no power in overdrive. I litterly have to floor it and get into passing gear to get my car to accelerate. I already changed the EGR cause I had that one coming up too. But the problem is still there

      • Frank

        In reply to: JIM

        Sound like a plugged catalytic converter. That would also be the cause of your EGR valve code.

      • gopinathan

        Sir, I own a Matiz 1999 model.My mechanic carried out engine reboring after observing heavy smoke through exhaust pipe. After reboring, the engine starts normally, but when we accelerate the engine, the fuel flow is getting chocked and the engine is not picking up .

      • Tech

        In reply to: gopinathan

        Hard to say. But sounds like your mechanic did not do something correctly. Timing could be off, bore too large, rings not seating, etc.

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