P0100
Mass or Volume Air Flow Circuit
- Severity
- Medium
- Driving
- Drivable — book it in
A fault in the mass airflow sensor circuit. This sensor measures how much air is entering the engine, and the module uses that figure as the basis for how much fuel to inject. When it is unreliable, fuelling is unreliable, so faults here tend to affect how the car drives rather than just emissions.
Possible causes
- CommonMass airflow sensor element dirty or contaminated
- CommonDamaged wiring or connector at the sensor
- CommonAir leak between the sensor and the throttle body
- PossibleFailed mass airflow sensor
- PossibleBadly fitted or aftermarket air filter letting dust through
What you might notice
- Hesitation or stumble under acceleration
- Rough idle
- Worse fuel economy
- Check engine light on
- Occasionally stalling
What to check, in order
- Inspect the intake ducting between the sensor and the throttle body for splits and loose clamps. Air entering after the sensor is never measured, which produces the same symptoms as a faulty sensor.
- Look at the sensor element. If it is visibly dirty, clean it with dedicated mass airflow sensor cleaner only - the hot-wire element is delicate and other solvents damage it.
- Check the air filter. A poorly fitting or oiled aftermarket filter is a common way sensors get contaminated.
- Inspect the connector and wiring for damage.
- Compare the airflow reading on the live data screen against expected values at idle before replacing the sensor.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering
P0100P0101P0102P0103P0104P0105P0106P0107P0108P0109P0110P0111P0112P0113P0114P0115P0116P0117P0118P0119P0120P0121P0122P0123P0124P0125P0126P0127P0128P0129P0130P0131P0132P0133P0134P0135P0136P0137P0138P0139P0140P0141P0142P0143P0144P0145P0146P0147P0148P0149P0150P0151P0152P0153P0154P0155P0156P0157P0158P0159P0160P0161P0162P0163P0164P0165P0166P0167P0168P0169P0170P0171P0172P0173P0174P0175P0176P0177P0178P0179P0180P0181P0182P0183P0184P0185P0186P0187P0188P0189P0190P0191P0192P0193P0194P0195P0196P0197P0198P0199