Rick's Free Auto Repair Advice

P0100 trouble code

P0100 trouble code is a MAF circuit malfunction

What is a P0100 trouble code

A P0100 Mass Airflow (MAF) Circuit Problem relates to a problem with the circuit servicing the mass airflow sensor. Common codes are P0101, P0102, P0103 and P0104. However, a P0100 code means

P0100 is the general code for a problem with the Mass Airflow (MAF) Sensor or Circuitry and the most common cause is a disconnected electrical connector or a problem with the terminals/pin in the connector or the wiring harness. However, it can also be caused by a bad MAF sensor.

Symptoms of a P0100 trouble code

When the PCM detects a problem with the MAF, the engine will run off of “imputed” values instead of live values from the MAF. Instead of proactively determining the best air fuel mixture, the PCM will take the information from the engine coolant temperature sensor, intake air temperate sensor (if the vehicle has one) and attempt to calculate proper air/fuel mixture. Then it will check the results from the oxygen sensors to see how well it did.

Since this method is nowhere near as accurate as live information from the MAF, you may notice:

The engine runs, but the idle may be rough or inconsistent, run erratically and have less power.

Diagnose a P0100 trouble code

First, check to make sure the MAF sensor plug is installed correctly. Often you’ll find this P0100 trouble code right after an oil change where the service technician had to remove the air filter cover and air duct to check the condition of the air filter. Then they forget to reconnect the MAF connector.

Next, check for battery voltage on the power wire coming into the MAF. If no power, check the fuse. Next check for good ground.

Finally, buying a MAF sensor, try cleaning it with a MAF sensor cleaner. See this post for step by step instructions. Since the MAF sensor is located in the air stream it can sometimes pick up particles that cause the sensor to provide incorrect readings.

Is the P0100 trouble code serious?

The P0100 trouble code won’t prevent your vehicle from starting or driving, but if the MAF isn’t working properly, you’ll get poor gas mileage and low power.

How difficult is a P0100 trouble code fix?

Any DIYer can replace the MAF sensor. It’s located in the air duct between the air filter box and the throttle body. Simply use a screwdriver to loosen the hose clamps at each end of the sensor. Then swap in the new sensor.

Maf sensor, mass airflow sensor, free wiring diagramMAF sensor readings

There 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 P0100 code means the computer has detected a circuit malfunction between the power or reference wire and ground.


© 2012 Rick Muscoplat



Posted on by Rick Muscoplat

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