Rick's Free Auto Repair Advice

P0103 trouble code

What causes a P0103 trouble code?

P0103 fuel volume regulator control circuit high

A P0103 trouble code can be defined two ways: P0103 fuel volume regulator control circuit high or P0103 – Mass Air Flow (MAF) Circuit High Input. The Mass Airflow Sensor (MAF) measures the temperature and volume by determining it’s density. Using the air density value, the computer can then determine how much fuel to add to the air.

Maf sensor, mass airflow sensor, free wiring diagramThere are two basic MAF sensor designs — analog and digital. The digital style usually uses three wires—12volt power, ground, and a third wire to carry the digital on/off signal to the computer. The on/off signal varies in frequency, depending on the amount of airflow through the MAF. To test a digital MAF you need an automotive scope.

In the analog design, the MAF puts out a variable voltage. These sensors can have up to five wires. These sensors can be tested with a computer safe test light.

A P0103 code means the computer has detected a value returning from the MAF that is outside the allowable range or is too high.

What causes a P0103 trouble code?

• MAF sensor screen is blocked
• MAF circuit shorted to VPWR
• Damaged MAF sensor
• Damaged PCM

Diagnose a P0103 trouble code

Check for battery voltage on the input wire. Check for good ground on the ground wire to the PCM. If you get a bad test on either, you’ve probably found the fault. If good, turn the key to RUN and backprobe the MAF sensor signal wire using a digital meter or scope, depending on the type of sensor used by the manufacturer. Refer to a shop manual for acceptable readings.

P0103 MAF sensor high


© 2012 Rick Muscoplat


Posted on by Rick Muscoplat

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