What it means
The ECU detects a general electrical malfunction in the mass air flow (MAF) sensor circuit. The signal is missing, out of plausible range, or the wiring shows continuity issues. Used as a generic fault when no more specific MAF code applies.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The mass air flow (MAF) sensor measures the air entering the engine, and the engine control module (ECM) uses its signal to calculate fuel delivery. P0100 sets when the ECM detects a general electrical or signal fault in the MAF circuit, rather than a specific low, high, or intermittent condition.
Common causes
Most likely first.
- MAF sensor element contaminated (oil, dust)
- MAF wiring or connector damaged
- Mass air flow sensor failed
Symptoms
- Check engine light on
How to diagnose it
- Read stored and pending codes and freeze-frame data, then compare live MAF readings with engine speed and load to see whether the signal is missing or implausible.
- With the engine off, inspect the MAF connector and harness for loose pins, corrosion, damage, or contamination on the sensing element.
- Check that the air duct and filter housing are assembled correctly and that the sensor is installed in the intended direction.
- Test MAF circuit power, ground, signal continuity, and shorts using the wiring diagram and manufacturer's specification.
- If the wiring checks out, clean the MAF only with an appropriate sensor cleaner if contamination is visible, then recheck live data.
- Replace the MAF sensor if its output remains faulty after the circuit and installation have been verified.
Common fixes
- Reconnect or repair a loose or damaged MAF connector or wire.
- Correct a poorly seated MAF sensor or intake duct connection.
- Clean a contaminated MAF element with suitable MAF cleaner, following the product instructions.
- Replace a MAF sensor that fails circuit and signal checks.
Can I keep driving?
A steady MIL with no drivability symptoms usually allows a short, gentle trip, but incorrect airflow data can worsen fuel economy and emissions. Avoid hard acceleration and address the fault soon; stop if the engine begins to stall or run roughly.
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.