Code
P0102
ISUZU
P — Powertrain
Mass Air Flow Circuit Low Input
Views:
UK: 38
EN: 48
RU: 65
AI status
Completed
Completed
100%
Causes
- Contaminated or failed MAF sensor (low output)
- Open or short to ground in the MAF signal wiring or connector
- Poor power or ground supply to the MAF sensor (blown fuse, corroded ground)
- Incorrect or loose connector pins / corrosion
- Intake air leaks downstream of the MAF (can alter readings)
- ECM input circuit fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Poor idle, rough running or stalling
- Reduced engine power or hesitation under acceleration
- Poor fuel economy or rich/lean running
- Hard starting in some conditions
What to check
- Read freeze frame data and live MAF sensor values with a scan tool
- Compare MAF voltage/frequency and calculated airflow to expected range at idle and various RPMs
- Inspect MAF connector and wiring for damage, corrosion, or loose pins
- Backprobe MAF connector to verify power (12V or reference), ground, and signal voltage
- Perform wiggle test on harness while observing live data to check intermittent faults
- Check for intake leaks between MAF and throttle/body
Signal parameters
- Typical MAF signal: ~0.5–1.5 V at idle (varies by design); rises with engine speed
- Wide open throttle: signal often approaches 4–5 V (design-dependent)
- Some MAFs use frequency output: low Hz at idle, higher with increased airflow (refer to vehicle spec)
- Power supply to sensor: 12 V or regulated reference (check vehicle wiring diagram)
- Ground: solid chassis/common ground (should be near 0 V)
Diagnostic algorithm
- Connect a scan tool, record freeze frame and live MAF values at key conditions (idle, 2000 rpm, WOT).
- Clear the code, run the engine and observe whether the code returns and how the MAF reading behaves.
- Visually inspect MAF sensor, connector and wiring for damage, oil or contamination; repair as needed.
- With ignition ON (engine off), backprobe the connector: verify sensor supply voltage and ground presence per vehicle specification.
- With engine running, measure MAF signal voltage or frequency and compare to expected ranges. Look for near‑zero or fixed low value.
- Perform a wiggle test of harness while monitoring live signal to identify intermittent open/shorts.
- Inspect intake tract for leaks or obstructions between air filter and throttle that could cause abnormal readings.
- Clean the MAF with approved cleaner if contaminated, then re-test. If no improvement, substitute a known-good MAF or replace the sensor.
- If wiring and replacement MAF are good but code persists, check ECU input circuit and perform further module diagnostics per manufacturer procedures.
Likely causes
- Dirty/contaminated MAF element (most common)
- Damaged wiring or poor connector connection at MAF (broken wire, pin pushed out)
- Failed MAF sensor
- Poor ground or supply voltage to the MAF
Fault status
Status
MAF sensor signal below expected range — ECM detects low/near‑zero airflow input from the MAF circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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