P0103: Mass or Volume Air Flow "A" Circuit High
The MAF sensor signal is higher than normal, so the computer thinks far more air is coming in than is possible.
What P0103 means
P0103 is the high side partner of P0102. The engine computer has seen the MAF signal stay above the top of its expected range. Since more airflow normally means more fuel, a falsely high reading can make the engine run rich, though RepairPal notes that many drivers notice no symptoms beyond the light. The usual causes are electrical: a signal wire shorted to a voltage source, a damaged connector, or a sensor that has failed internally. Shops record the freeze frame data and compare the MAF reading to engine RPM and throttle position. A quick check is to unplug the sensor with the key on; if the reading stays high, the wiring is suspect. They then test each wire at the connector against a wiring diagram. RepairPal lists replacing the sensor when the wiring is bad as a common misdiagnosis. Fixing it is usually straightforward once the circuit has been tested, and it should restore normal fuel economy.
Common symptoms
- Check engine light on
- Often no driveability change
- Poor fuel economy
- Possible black smoke or rich running
- Rough idle on some vehicles
Most common causes
- Signal wire shorted to voltage
- Corroded or damaged MAF connector
- Failed MAF sensor
- Wiring harness rubbing on engine parts
- Aftermarket intake that changes airflow over the sensor
What to check yourself first
Inspect the harness from the MAF sensor for chafed spots or wires melted against hot parts. Check that the connector is not cracked or full of water. If you installed a cold air intake recently, note that some designs upset MAF readings.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | RepairPal notes MAF sensors are often replaced when the real cause was bad wiring or a bad connector. |
| Replace mass airflow (MAF) sensor | $274-$381 | If the sensor itself puts out high voltage with good wiring. |
| Clean the MAF sensor yourself | $15-$20 | Cheap first step if the element is contaminated, about $17. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0100 Mass or Volume Air Flow "A" Circuit
- P0101 Mass or Volume Air Flow "A" Circuit Range/Performance
- P0102 Mass or Volume Air Flow "A" Circuit Low
- P0172 System Too Rich (Bank 1)
- P0113 Intake Air Temperature Sensor 1 Circuit High