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Home / DTC / P0102 — Mass or Volume Air Flow Sensor A Circuit Low

P0102 — Mass or Volume Air Flow Sensor A Circuit Low

Detailed page for trouble code P0102.

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P0102

Generic P — Powertrain

Mass or Volume Air Flow Sensor A Circuit Low

Brand: Generic
Type: P — Powertrain
Views: UK: 46 EN: 74 RU: 81
AI status
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Page language: EN

Causes

  • MAF sensor signal shorted to ground
  • Open or corroded connector or poor terminal contact
  • Failed or internally shorted MAF sensor
  • Contaminated MAF sensing element (dirt/oil) or sensor drift
  • Severely clogged air filter or intake restriction
  • Intake leaks downstream of the MAF (affecting expected readings)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor idle or rough idle
  • Hesitation or stumbling on acceleration
  • Reduced engine power or limp-home mode
  • Higher than normal fuel trim (lean) or drivability complaints
  • Stalling at low speed or hard starting in some cases

What to check

  • Read and record freeze frame and live data (MAF value, engine RPM, throttle position, engine load, short-term fuel trim)
  • Visual inspection of air intake, air filter, MAF housing and sensor connector for contamination, damage, or loose clamps
  • Inspect wiring harness for chafing, pinched wires, or evidence of shorting especially where harness is routed
  • Check for proper connector seating, bent pins, corrosion or moisture in connector
  • Verify sensor supply voltage, reference and ground at key-on and engine running
  • Backprobe MAF signal and compare live signal to expected behavior while revving engine

Signal parameters

  • Typical MAF sensor output: 0.5–4.5 V (varies by vehicle and sensor type); at idle many systems show ~0.5–2.0 V
  • Hot-wire MAF may report mass flow in g/s (idle commonly a few g/s; increases with RPM/load) — values vary by engine
  • Frequency-style sensors may show 0–1,000+ Hz depending on airflow
  • A 'low' circuit means the measured signal (voltage/frequency/g/s) is lower than the PCM's expected window for the measured RPM/TP

Diagnostic algorithm

  1. Verify code(s) and capture freeze frame/live data. Note engine speed, throttle position, MAF value and fuel trims when code set.
  2. Visually inspect air inlet, air filter and MAF sensor for contamination, oil on element, or physical damage. Replace/clean as appropriate.
  3. With key off, disconnect MAF connector and inspect pins for corrosion or damage. Reconnect securely.
  4. Check power and ground circuits: with key on measure reference power (usually 12 V switched or regulated supply) and good ground continuity to chassis and PCM.
  5. Backprobe signal wire with engine running. Observe voltage/frequency/mass-flow values while varying RPM and throttle — values should rise smoothly with increased airflow. Wiggle harness to check intermittent faults.
  6. If signal is stuck low or near 0 V, test for short to ground: disconnect sensor and measure continuity from signal wire to ground. Repair short if present.
  7. If wiring and supplies are good but output remains low, clean the MAF with approved MAF cleaner and retest. Do not use other cleaners.
  8. If cleaning does not restore proper signal, swap with a known-good MAF (if available) or replace the MAF sensor and retest.
  9. If new sensor also shows low signal and wiring/power/ground verified, suspect PCM input fault and perform PCM diagnostics or consult manufacturer procedures.
  10. After repair clear codes and perform a road test while monitoring MAF and fuel trims to confirm correct operation.

Likely causes

  • Wiring short to ground on MAF signal circuit
  • Corroded/loose connector or damaged harness near the sensor
  • Contaminated MAF element (oil from aftermarket intake filters, dirt)
  • Failed MAF sensor
  • Clogged air filter or intake restriction reducing actual airflow

Fault status

⚠️ Status
MAF Sensor 'A' Circuit Low — MAF output lower than expected for operating conditions (possible short to ground, wiring/connector fault, contamination, or failed sensor).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5–2.5 hours

Similar codes

P0100 P0101 P0103 P0113 P0114
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