P0100: Mass or volume air flow sensor circuit fault

What P0100 means

The air flow sensor (often called the MAF) measures how much air enters the engine so the ECU can work out how much fuel to inject. This code points to a general fault in its circuit: the signal is missing or makes no sense. Without it the ECU uses backup values and the engine runs less well.

Most common causes

• Loose, corroded or damp air flow sensor connector
• Broken or chafed sensor wire
• A faulty air flow sensor
• Missing power or earth at the sensor (fuse or relay)
• A loose intake hose next to the sensor that has shifted it

Symptoms

• Engine warning light on
• Loss of power or sluggish response
• Unstable idle or stalling
• Higher fuel consumption

Can you drive with P0100?

With care You can drive, but the engine is running on backup data and may feel flat or use more fuel. Get it fixed soon.

How to check it

In live data, check air flow (in g/s): it should be steady at idle and rise when you accelerate. If it reads zero or a fixed value that never changes, the problem is in the circuit or the sensor.

How to read and clear P0100 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0100 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0101 Air flow sensor range or performance problem
• P0102 Air flow sensor circuit low input
• P0103 Air flow sensor circuit high input
• P0104 Air flow sensor circuit intermittent
• P0105 Manifold absolute pressure (MAP) sensor circuit fault
• P0106 Manifold absolute pressure (MAP) sensor range or performance
• P0107 Manifold absolute pressure (MAP) sensor circuit low
• P0108 Manifold absolute pressure (MAP) sensor circuit high

P0100 is a generic code, so it means the same on any make, for example on Abarth, Citroën, Hyundai, Mini, Seat, Volvo. See what Final OBD does on your car in makes and models.