P0102 - Mass Air Flow (MAF) Circuit Low Input
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0102 is set when the Engine Control Module (ECM) detects a signal voltage from the Mass Air Flow (MAF) sensor that is lower than the expected operating range (typically below 0.2V to 0.5V). The MAF sensor measures the volume and density of air entering the engine, which the ECM uses to determine fuel delivery and ignition timing. A low input signal usually indicates an open circuit, short to ground, or a severely contaminated sensor element that fails to respond to airflow.
Possible Causes
Faulty or contaminated MAF sensor (e.g., oil residue from aftermarket filters)
Wiring issues (open circuit or short to ground in the signal wire)
Blown fuse or faulty relay providing power to the sensor
Severe vacuum leak after the sensor or a severely restricted air intake/filter
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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