What it means
The MAF sensor reports an air flow value below the plausible minimum for current engine speed and load. The ECU substitutes a calculated load value while the fault is active.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The MAF sensor measures the air entering the engine, and the ECM uses that signal to set fueling. P0102 sets when the signal voltage or reported airflow is below the expected minimum for the current engine conditions, so the ECM may use a substitute load estimate.
Common causes
Most likely first.
- MAF sensor failed
- MAF connector loose or disconnected
- Signal wire shorted to ground
Symptoms
- Check engine light on
How to diagnose it
- Check freeze-frame data and live MAF readings at key-on, idle, and a brief increase in RPM to confirm the signal stays unusually low.
- With the ignition off, check that the MAF connector is fully seated and inspect its pins and harness for damage, corrosion, or a wire pulled loose.
- Inspect the signal wire for a short to ground and check circuit power and ground using the wiring diagram and manufacturer's specification.
- Verify the MAF sensor and intake duct are installed correctly and that the sensing element is not contaminated.
- If circuit integrity and connections are good, compare the sensor output with the manufacturer's specification and replace the sensor only if it remains low.
Common fixes
- Reconnect a loose MAF connector or repair damaged terminals.
- Repair a signal wire shorted to ground or another damaged section of the harness.
- Clean a visibly contaminated MAF element with suitable MAF cleaner, following the product instructions.
- Replace a MAF sensor that produces a low output despite correct circuit power, ground, and wiring.
Can I keep driving?
A short, gentle drive may be possible if the engine runs smoothly, but avoid hard acceleration because the ECM may be estimating engine load. Stop if it stalls, hesitates severely, or runs roughly, and arrange repair soon.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.