P0101: Mass Air Flow (MAF) Circuit Range/Performance

What Does The P0101 Code Mean?

The MAF (mass air flow) sensor is a sensor mounted in a vehicle’s engine air intake tract downstream from the air filter, and is used to measure the volume and density of air being drawn into the engine. The MAF sensor itself only measures a portion of the air entering and that value is used to calculate the total volume and density of air being ingested.

The powertrain control module (PCM) uses that reading along with other sensor parameters to ensure proper fuel delivery at any given time for optimum power and fuel efficiency.

Basically this P0101 diagnostic trouble code (DTC) means that there is a problem with the Mass Air Flow (MAF) sensor or circuit. The PCM detects that the actual MAF sensor frequency signal is not within a predetermined expected range of the calculated MAF value.

Note: Some MAF sensors also incorporate an air temperature sensor, which is another value used by the PCM for optimal engine operation.

Closely related MAF circuit trouble codes include:

• P0100 Mass or Volume Air Flow “A” Circuit Malfunction
• P0102 Mass or Volume Air Flow “A” Circuit Low Input
• P0103 Mass or Volume Air Flow “A” Circuit High Input
• P0104 Mass or Volume Air Flow “A” Circuit Intermittent

What Are The Symptoms Of The P0101 Code?

Symptoms of a P0101 code may include:

• Malfunction indicator lamp (MIL) illumination (a.k.a. check engine light)
• Rough running engine
• Black smoke from tail pipe
• Stalling
• Engine hard start or stalling after it starts
• Possible other driveability symptoms

What Are The Potential Causes Of The P0101 Code?

Potential causes for this trouble code may include:

• Dirty or contaminated mass air flow sensor
• Failed MAF sensor
• Intake air leaks
• MAF sensor electrical harness or wiring problem (open, shorted, frayed, poor connection, etc.)
• Clogged catalytic converter on some models (/Chevrolet mainly)

Note that other codes may be present if you have a P0101. You may have misfire codes or O2 sensor codes, so it’s important to take a “big picture” look at how the systems work together and effect each other when doing a diagnosis.

How Can You Fix The P0101 Code?

Possible diagnostic and repair steps include:

• Visually inspect all MAF sensor wiring and connectors to make sure they are intact, not frayed, broken, routed too close to ignition wires/coils, relays, motors, etc.
• Visually inspect for any obvious air leaks in the air intake system
• Visually *closely* inspect the MAF sensor wires or film to see if you can see contamination such as dirt, dust, oil, etc.
• If the air filter is dirty, replace it
• Carefully clean the MAF using MAF cleaner sprayis generally a good DIY friendly diagnostic/repair step
• If the air intake system has a mesh in it, make sure that is also clean (VWs mainly)
• Loss of vacuum to the MAP sensor can trigger this DTC
• A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
• Use a scan tool to monitor real-time sensor values from the MAF sensor, O2 sensors, etc.
• Check for Technical Service Bulletins (TSBs) for your particular make/model in case of known issues on your vehicle
• The barometric pressure (BARO) that is used in order to calculate the predicted MAF value is initially based on the MAP sensorat key ON.
• A high resistance on the ground circuit of the MAP sensorcan cause this DTC to set
• Do an exhaust backpressure test to determine if the catalytic converter may be clogged

If you do need to replace the MAF sensor, we recommend using an original equipment OEM one from the manufacturer rather than buying an aftermarket part.

Note: The use of a reusable oiled air filter could be a cause of this code, if it is over-oiled. Oil can transfer to the fine wire or film inside the MAF sensor and contaminate it. Use something such as MAF cleaner sprayto clean the MAF in such situations.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> MAF Sensor
>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> Dorman 86689C 399 PC Automotive Electrical Repair Kit

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Check This Video For Reference

P0101 Infographic - 1 Minute Summary

Reference Sources

Diagnostic Trouble Code (DTC) Charts and Descriptions for P0101 – Page 20.