P0100 OBD2 Code:  Meaning, Causes, + How to Fix

P0100 is a generic OBD2 trouble code that indicates an issue with your vehicle’s Mass Air Flow (MAF) Sensor.  

This code is usually caused by a MAF sensor that is faulty, dirty or a wiring issue related to it. It may be tempting to replace the MAF sensor without checking the electrical system and cleaning/testing it first, but it’s not guaranteed to clear P0100.

P0100 Quick Info Table

DefinitionP0100: Mass or Volume Air Flow (MAF) Circuit Malfunction
Frequent SymptomsAir Fuel Mixture Too Rich or Lean, Stalling, Can’t Find Idle, MIL Light
Common CausesBad or Dirty MAF Sensor, MAF Sensor Wiring, Vacuum Leak
Breakdown Risk?Yes
Repair DifficultyModerate
Estimated Repair Cost (Parts)Less than $200

P0100 Meaning

A typical MAF Sensor

P0100: Mass or Volume Air Flow (MAF) Circuit Malfunction

P0100 is a generic code, so it has the same meaning for any vehicle with an OBD II system (1996+).

Mass or Volume Air Flow

The MAF sensor is responsible for metering the air entering the engine (density and volume). It compares the airflow measurement to a voltage value that the powertrain control module (PCM) understands.

Circuit Malfunction

P0100 indicates that the voltage value sent to the PCM is outside its normal operating range.


Here are the most common symptoms associated with the P0100 code:

  • Engine running rich or lean–  A lean or rich condition can happen at idle speed or high RPM.
  • Fluctuating idle RPM– When the PCM can’t determine how much air enters the engine, it’ll have difficulty keeping a consistent idle speed.
  • Check Engine Light– P0100 usually appears with other fault codes, such as P0171 or P0172.
  • Stalling

P0100 Causes + Diagnosis

P0100 Causes

Here are the most common causes of P0100, presented to you from the easiest to most difficult to check.

1. Check the Electrical Connection

No matter the vehicle, the MAF sensor is usually pretty easy to get to. It’ll be between the air filter and the throttle body. First, perform a visual inspection of the ground connection, feeds, and wiring.

MAF sensor wiring is often the victim of rodent damage (particularly in the winter).

2. Listen for a Vacuum Leak

If there is a leak in the intake manifold, it will be impossible for the MAF sensor to get an accurate reading. Without knowing how much air is getting into the engine, P0100 can be thrown.

Inspect the air intake system and intake manifold for obvious air leaks.

3. Check to See if the MAF Sensor is Dirty

Throughout its life, the MAF sensor will often get so covered in grime that it’ll no longer get an accurate reading. You can clean it, but you must use a dedicated MAF cleaner spray. Here’s a great article on how to clean one from Family Handyman: MAF Sensor Cleaning

Oiled air filters (such as K&N) can cause the MAF sensor to get dirty. If you use that type of filter on your vehicle, checking it should be the first thing you should do when you get P0100.

4. Test the MAF Sensor

While it is very likely that the MAF sensor itself could be the problem, test it before replacing it. Here’s a video on how to test one without pulling it. Testing it is important for two reasons. The first is that they are expensive. The second is that it only takes a few minutes to test it with a multimeter. They are usually around $200 or less if you need one.