P0102 code meaning
Mass or Volume Air Flow Sensor A Circuit Low
Powertrain system Generic code P01xx codes Check engine light
What P0102 means
The mass air flow sensor (MAF) sits between the air filter and the throttle or compressor and measures how much air the engine draws in; fuel quantity, load and ignition are calculated from it. Most are hot-film or hot-wire sensors that output either a voltage or, on GM, Saab and newer Ford systems, a frequency. P0102 means the signal is below its electrical lower limit – a frequency that is too low or a voltage that is too low. Documented limits: GM gasoline 450 Hz or less, GM diesel below 276 Hz, Ford digital below 1.5 kHz for 5 s, Ford analogue below 0.244 V. 'Low' describes the signal: typically an open or grounded signal wire, missing supply voltage or failed electronics. Saab notes that a large leak between sensor and throttle can also cause it. GM and Saab need two trips; the engine runs on a calculated substitute value.
P0102 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0102
- Check engine light on
- Lack of power, hesitation, substitute value mode
- Rough idle or stalling
- Higher fuel consumption
Common causes of P0102
- Most likelySignal wire open or shorted to ground, connector corroded or loose
- Most likelySensor electronics failed
- PossibleMissing supply voltage (fuse, relay) or poor ground
- Less likelyLarge leak or disconnected duct between sensor and throttle
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Mass air flow sensorMass air flow sensor wiringSensor supply voltage
What each part of P0102 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 02 | The exact fault in that area. |
What to do next
- Note P0102 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0102
What does P0102 mean?
P0102 means "Mass or Volume Air Flow Sensor A Circuit Low". The mass air flow sensor (MAF) sits between the air filter and the throttle or compressor and measures how much air the engine draws in; fuel quantity, load and ignition are calculated from it. It is a generic code, so it means the same on every make.
Is it safe to drive with P0102?
Drive gently and only to a workshop. With P0102 the car can go into limp mode (reduced power) to protect itself.
Will P0102 fail an emissions test?
Yes, it can. P0102 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0102 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0102 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.