P0101
Mass or Volume Air Flow Circuit Range/Performance
- Severity
- Medium
- Driving
- Drivable — book it in
The mass airflow sensor is working, but its reading does not agree with what the module expects from engine speed and throttle position. The signal is plausible in isolation and wrong in context - which usually means the sensor is drifting, or air is bypassing it.
Possible causes
- CommonDirty mass airflow sensor reading low
- CommonAir leak between the sensor and the engine
- PossibleRestricted air filter
- PossibleExhaust restriction, for example a blocked catalytic converter
- PossibleFailed mass airflow sensor
What you might notice
- Hesitation under acceleration
- Lack of power
- Rough idle
- Worse fuel economy
- Check engine light on
What to check, in order
- Check the intake ducting for leaks first - a split in the pipe after the sensor is the most common cause.
- Clean the sensor element with mass airflow sensor cleaner.
- Check the air filter is clean and correctly seated.
- Compare the airflow reading against expected values at idle and at higher engine speed. A sensor that reads plausibly at idle but low under load is drifting.
- If the car feels strangled at higher speeds, consider a blocked exhaust or converter.
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