What Does P0102 Mean?
The mass air flow sensor 'A' circuit is reporting a voltage or frequency signal that is lower than the minimum expected threshold. The PCM interprets this as extremely low or zero airflow, which is implausible when the engine is running. This typically indicates an electrical problem such as an open signal wire, failed sensor, or poor ground. The driver will notice rough idle, stalling, hesitation, poor fuel economy, and possible black smoke from an overly rich condition as the PCM defaults to a richer map.
Common Causes
30%
Open or high-resistance connection in the MAF sensor signal wire
25%
Failed MAF sensor with no signal output
20%
Poor ground connection at the MAF sensor
15%
Heavily contaminated MAF element reading near zero
10%
Aftermarket air intake allowing contamination or incorrect MAF housing diameter
Diagnostic Steps
1
Check the MAF PID in live data — a constant 0 g/s or near-zero reading with the engine running confirms a circuit issue; very low but non-zero may indicate contamination.
2
Verify the MAF sensor is plugged in and the connector lock is engaged — vibration can work connectors loose over time.
3
Back-probe the MAF signal wire at the sensor connector — with the engine running, a hot-wire MAF should show 0.5-1.0V at idle; 0V indicates no signal output.
4
Check the ground circuit by measuring voltage drop between the MAF sensor ground pin and battery negative with the engine running — should be less than 0.1V.
5
If the sensor has power and ground but no signal, replace the MAF sensor; if the sensor has no power, trace the power supply circuit back to the fuse and relay.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The mass air flow sensor 'A' circuit is reporting a voltage or frequency signal that is lower than the minimum expected threshold. The PCM interprets this as extremely low or zero airflow, which is implausible when the engine is running. This typically indicates an electrical problem such as an open...
The most common cause of P0102 (Mass or Volume Air Flow "A" Circuit Low Input) is: Open or high-resistance connection in the MAF sensor signal wire
Typical repair costs for P0102 range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may stall unexpectedly, particularly at idle or low speeds. The PCM will use a default airflow calculation but drivability will be significantly impaired. Drive cautiously to a repair shop; avoid situations requiring full acceleration or immediate throttle response.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0102 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel / Air Metering System
Difficulty
Type
Generic (SAE)
Recommended Tools
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