P0101: Mass air flow circuit range/performance
The air flow (MAF) sensor reading does not match what the engine computer expects.
Updated
What P0101 means
The air flow (MAF) sensor measures how much air the engine draws in, and the engine computer uses it to work out how much fuel to inject. It also knows roughly how much air to expect from the engine speed, the throttle and, on many cars, the intake pressure.
“Range/performance” means the sensor’s signal is there, but it doesn’t fit that expectation. The computer stores P0101 and, on many cars, falls back on a calculated value.
Read My Car’s live data shows the air flow in g/s, if your car reports it.
P0100, P0102, P0103 and P0104: circuit faults
These codes mean the sensor’s signal itself is faulty: a fault in the circuit (P0100), too low (P0102), too high (P0103) or dropping out (P0104). Start with the plug and the wiring, then the sensor. Most engines then run on a calculated value, but some hesitate, barely idle or stall: if yours does, have it checked before driving on.
P0100: Mass air flow circuit malfunction
The engine computer gets no usable signal from the air flow (MAF) sensor: it’s missing, too low, too high or drops out. Most engines then run on a calculated value, but some hesitate, idle badly or stall.
Common causes: wiring or connector fault, dirty or faulty maf sensor, split or loose intake duct near the sensor.
Driving: Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse. If the engine hesitates badly, stalls or barely idles, don’t drive on: have it checked first.
P0102: Mass air flow circuit low input
The engine computer gets no usable signal from the air flow (MAF) sensor: it’s missing, too low, too high or drops out. Most engines then run on a calculated value, but some hesitate, idle badly or stall.
Common causes: wiring or connector fault, dirty or faulty maf sensor, split or loose intake duct near the sensor.
Driving: Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse. If the engine hesitates badly, stalls or barely idles, don’t drive on: have it checked first.
P0103: Mass air flow circuit high input
The engine computer gets no usable signal from the air flow (MAF) sensor: it’s missing, too low, too high or drops out. Most engines then run on a calculated value, but some hesitate, idle badly or stall.
Common causes: wiring or connector fault, dirty or faulty maf sensor, split or loose intake duct near the sensor.
Driving: Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse. If the engine hesitates badly, stalls or barely idles, don’t drive on: have it checked first.
P0104: Mass or Volume Air Flow Sensor A Circuit Intermittent
The engine computer gets no usable signal from the air flow (MAF) sensor: it’s missing, too low, too high or drops out. Most engines then run on a calculated value, but some hesitate, idle badly or stall.
Common causes: wiring or connector fault, dirty or faulty maf sensor, split or loose intake duct near the sensor.
Driving: Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse. If the engine hesitates badly, stalls or barely idles, don’t drive on: have it checked first.
Can I keep driving?
Check soon
Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
The engine usually keeps running, sometimes with less power or an uneven idle. Lean or rich codes (P0171, P0172) stored with it often have the same cause.
Symptoms
- Often just the check engine light.
- Hesitation or less power when accelerating.
- On some cars, a rough idle, stalling or higher fuel use.
Common causes
- Dirty MAF sensor. Dust or oil on the sensing element makes it misread the air.
- Air leak after the sensor. Air that gets in between the sensor and the engine isn’t measured. Check the ducting and its clamps.
- Clogged air filter. It restricts the air flow. Easy to check, so rule it out first.
- Wiring or connector fault. A loose or corroded plug can distort the signal.
Typical fixes
- Check the air filter, and the ducting between the sensor and the engine for splits and loose clamps.
- Check the sensor’s plug for a firm fit and corrosion.
- Clean the sensor with a cleaner made for air flow sensors, without touching the sensing element.
- Compare the air flow at a warm idle with the rough guide in the live data guide, and replace the sensor if it still reads wrong.
Questions
Can I drive with P0101?
Probably for a short time, but have it checked soon: the app’s advice is that fuel use or emissions may be worse. If the engine stalls or hesitates badly, have it checked before driving far.
Can cleaning the MAF sensor fix P0101?
It can, if dirt is the cause. Use a cleaner made for air flow sensors and don’t touch the sensing element. If the code comes back, check for air leaks and the wiring.