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P0102 — MAF Sensor Low Input

P0102 is set when the ECM sees the mass air flow sensor signal at a voltage or frequency below the calibrated minimum for the engine's operating conditions. Where P0101 means "MAF reading is implausible", P0102 means "MAF signal is too low or missing entirely." The cause is usually a disconnected sensor, broken signal wire, or a sensor that has failed in a way that produces no output.

P0102 means maf sensor low input. A vehicle usually stays drivable short-term with this code, but it should be diagnosed promptly. The most common cause is disconnected maf sensor connector (typically $0–$50). Causes and cost vary by make and model; confirm the root cause before replacing parts.

Severity: moderate powertrain Safe to drive (short term)

Reviewed by MECH AI Editorial · Last verified

What does P0102 mean?

P0102 is set when the ECM sees the mass air flow sensor signal at a voltage or frequency below the calibrated minimum for the engine's operating conditions. Where P0101 means "MAF reading is implausible", P0102 means "MAF signal is too low or missing entirely." The cause is usually a disconnected sensor, broken signal wire, or a sensor that has failed in a way that produces no output.

What are the symptoms of P0102?

What causes P0102?

Cause Likelihood Estimated repair (USD)
Disconnected MAF sensor connector — Check this first — the simplest cause is the most common after recent work. Most common $0–$50
Broken or shorted MAF signal wire Common $80–$350
Corroded MAF sensor connector pins Common $30–$200
Internal MAF sensor failure (sensor produces no output) Common $80–$450
Open in MAF sensor 5 V reference or ground supply Occasional $100–$400
Failed PCM input circuit for the MAF (rare) Rare $400–$1,500

Repair costs are typical US ranges and vary by make, model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.

Is it safe to drive with P0102?

In most cases a vehicle stays drivable for short trips with P0102 active, but you should diagnose and repair it promptly. This is a moderate-severity code — ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on your specific make and model.

How to diagnose P0102

  1. Verify the MAF connector is fully seated

    A loose or unlatched MAF connector is the #1 cause of P0102 after recent under-hood work — air filter changes, intake cleaning, or a previous diagnostic. Press the connector firmly until the latch clicks. Clear the code and drive.

    Tools: None

  2. Read MAF signal voltage or frequency

    On a standard hot-wire MAF, the signal should read about 0.6 V at key-on engine-off and climb to 1.5–2.5 V at idle. A stuck reading below 0.3 V at idle confirms a low-input fault. On digital MAFs the scan tool will report frequency in Hz instead — typical idle readings are 2.5–3.5 kHz.

    Tools: Scan tool with MAF voltage / frequency PID, Multimeter (back-probe capable)

  3. Test the MAF power, ground, and signal wires

    Back-probe the MAF connector with a multimeter. Verify: battery voltage on the supply wire with key on, continuity from the ground wire to engine ground, and an open or short on the signal wire to the PCM. A missing supply voltage points to a blown fuse or harness fault.

    Tools: Multimeter, Back-probe pins, Wiring diagram

  4. Inspect the connector pins

    Unplug the MAF and look closely at the pins inside the connector. Green corrosion, bent terminals, or evidence of water intrusion will cause intermittent or low signal. Clean with electrical contact cleaner and bend terminals straight if needed.

    Tools: Electrical contact cleaner, Pick tool, Magnifying glass

  5. Swap or test the MAF sensor

    If wiring and power supply test good and the connector is clean, the MAF sensor is the prime suspect. Swap with a known-good unit if available, or install a new OEM sensor. Avoid the cheap eBay MAFs — they fail at very high rates.

    Tools: Socket / driver to remove MAF

How do I fix P0102?

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P0102: frequently asked questions

What does diagnostic trouble code P0102 mean?

P0102 is set when the ECM sees the mass air flow sensor signal at a voltage or frequency below the calibrated minimum for the engine's operating conditions. Where P0101 means "MAF reading is implausible", P0102 means "MAF signal is too low or missing entirely." The cause is usually a disconnected sensor, broken signal wire, or a sensor that has failed in a way that produces no output.

What are the symptoms of P0102?

Check Engine Light is illuminated. Hesitation, stumble, or stall on acceleration. Hard starting or extended crank time. Reduced power and throttle response. Black smoke or rich smell from exhaust (ECM defaults to a rich limp map). Reduced fuel economy

What causes P0102?

Disconnected MAF sensor connector (most-common). Broken or shorted MAF signal wire (common). Corroded MAF sensor connector pins (common). Internal MAF sensor failure (sensor produces no output) (common). Open in MAF sensor 5 V reference or ground supply (occasional). Failed PCM input circuit for the MAF (rare) (rare)

Is it safe to drive with P0102?

In most cases a vehicle stays drivable for short trips with P0102 active, but it should be diagnosed and repaired promptly — this is a moderate-severity code. Ignoring it can lead to further damage or a failed emissions test. Specific tolerance varies by make and model.