P0102 — MAF sensor A — low electrical input

P0102 indicates an abnormally low electrical input from the mass-air-flow (MAF) circuit designated A. It does not by itself confirm genuinely low air flow, a blocked filter or a failed sensor. Sensor outputs vary (analogue, frequency or digital), so interpret pin signals and reference limits from the VIN-specific service information.

Affected system: Powertrain

Symptoms

• Engine warning lamp; DTC may be active or historical.
• Reduced power, hesitation or an ECU-calculated substitute airflow value.
• Rough idle or stall on some systems; other vehicles may show no obvious drivability problem.

Possible causes

• Missing MAF feed or ground, intermittent terminal contact or corroded connector.
• Open or grounded signal wire, or incorrect digital/frequency interface; the signal type determines the fault interpretation.
• Contaminated or damaged measuring element or wrong installation; inspect intake-air path separately if associated codes point there.

What to check

• 1. Record active/history status, freeze-frame and companion faults. A moisture- or service-related intermittent event prioritizes terminals and harness.
• 2. Identify MAF A and its output design from VIN-specific documentation (analogue, frequency or digital). Do not apply a universal voltage or pin assignment.
• 3. Examine mounting, air duct seal, connector pins and harness. Loose or wet terminals should be repaired before sensor replacement.
• 4. Check supply and ground under the specified conditions. A missing feed or ground identifies an external circuit fault, not proof of failed MAF electronics.
• 5. With controllers isolated according to OEM instructions, check signal-path continuity and shorts separately. An open or grounded wire can account for low input.
• 6. Compare scan-tool MAF with RPM/load and freeze-frame conditions. A frozen or implausible value may be ECU substitution; verify the actual signal before interpreting it as measured airflow.
• 7. On a compatible architecture, observe the correctly identified output at the sensor and ECU using the prescribed instrument. Sensor-side signal present but ECU-side absent points to wiring; both absent with correct feeds warrants sensor evaluation.
• 8. Inspect the sensing element without touching it or applying unapproved solvent. Replace the correct part only if contamination or hardware fault is demonstrated; repair intake faults only if confirmed.

Also written as: P0102-00, P010200, PO102 (some scan tools add the fault-type byte, e.g. -00).