What it means
The MAF sensor reports an air flow value above the plausible maximum for current engine speed and load. Often indicates a sensor that is failing in a way that produces excess output, or a short to supply voltage in the signal path.
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 incoming air, and the ECM uses its output to calculate engine load and fueling. P0103 sets when the signal rises above the expected maximum for the current conditions, which can result from an excessive sensor output or a signal circuit shorted toward supply voltage.
Common causes
Most likely first.
- MAF sensor failed
- Signal wire shorted to supply voltage
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
How to diagnose it
- Review freeze-frame data and live MAF readings at key-on and idle to establish whether the signal is fixed high or rises implausibly with engine operation.
- Inspect the MAF connector for corrosion, bent or spread terminals, and poor contact; check the harness for damage or contact with a power source.
- Use the wiring diagram to test the signal circuit for a short to supply voltage and check sensor ground and power against the manufacturer's specification.
- Inspect the MAF sensor for contamination and verify it is correctly installed in the intake duct.
- If wiring, connector contact, and ground are sound, compare sensor output with the manufacturer's specification to determine whether the MAF itself is producing excessive output.
Common fixes
- Repair a signal wire shorted to supply voltage or other damaged harness section.
- Clean corrosion from the connector or repair terminals that do not make sound contact.
- Restore a faulty sensor ground or connector connection.
- Clean a contaminated MAF element with suitable MAF cleaner, following the product instructions.
- Replace the MAF sensor if its output remains high with a correctly tested circuit.
Can I keep driving?
Limit driving to a short, gentle trip if the engine runs smoothly; an excessive airflow reading can lead to incorrect fueling and poor running. Avoid high-load driving and stop if the engine misfires, stalls, or loses power.
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.