Error Code P0100 is described as a Mass Airflow (MAF) Circuit Malfunction, which basically refers to a problem in the electrical circuit between the MAF sensor and the PCM (powertrain control module, also known as ECM or electronic control module).

This error code is a generic code associated with MAF sensor circuit  trouble codes, such as P0101, P0102, P0103 and P0104.

Definition

The MAF is placed in the stream of intake air. Its job is to measure the rate of intake flow (meaning the air entering the engine) by measuring a part of the whole intake flow. It is made up of a hot film and is supplied with electric current from the PCM, the temperature of which is also controlled by the latter. The heat generated by the film is reduced as intake air flow through it. The more air that enters, the greater the heat loss. Thus, as air flow increases, the PCM needs to supply the right level of temperature to the hot film.

The information gathered by the MAF sensor is important for the PCM to calculate the proper amount of fuel and timing for ignition. The Error Code P0100 is set when the PCM detects a problem in the electrical circuit that connects the PCM and the MAF sensor, and the data output from the sensor disappears or becomes erratic.

Common Symptoms

Because this error code affects the MAF sensor, it most definitely causes several drivability issues such as sluggishness and general decrease of power. That’s of course, aside from the triggered Check Engine light on the dashboard display. Other symptoms include:

  • Inconsistent idle
  • Poor engine performance, rough running
  • Stall or hesitate upon acceleration
  • Poor fuel mileage
  • Excessive smoke

Possible Causes

Problems with the MAF sensor can be caused by different things, but the most common cause for this error code is usually related to the disconnected electrical plug or damaged wiring at the plug. Other possible causes include:

  • Defective or damaged MAF sensor
  • Corroded or loose electrical terminals in MAF sensor circuit

How to Check

Certified mechanics start their diagnosis using their OBD-II scanner. They will then reset the fault codes and then take the vehicle for a test drive to see if the error code comes back.

If the code comes back, then the technician will conduct a thorough visual inspection on the electrical connector, wiring or sensor issues.

How to Fix

The simplest fix for this error code is to reset the code and see if it comes back in your test drive. From there, you can start with the easy repairs. The most common repairs for this error code are as follows:

  1. Check all the electrical connector and wirings to the MAF sensor and make sure everything is attached to their designated ports. Then, disconnect and reconnect connector to refresh electrical connection of the MAF wiring harness.
  2. Repair any broken or frayed wirings on the connector.
  3. Check MAF sensor’s voltage. Refer to the vehicle’s manual for specific information.
  4. Replace the MAF sensor.

Parting Tips

Error Code P0100 will not prevent the vehicle from running. However, it can cause excessive fuel consumption, thus, it’s always best to have a qualified technician to do the thorough diagnosis and repair for you.

Also, sometimes when the Check Engine light is on at start up, simply reset the OBD-II system and let the vehicle get back to normal.

Many people when they see this error code, jump into replacing the MAF sensor, when in fact, it’s a vacuum leak, misfiring engine or defecting connector and/or wiring harness that are causing the error code. Thus, a proper diagnosis is extremely important.