Summary
P0103 means the MAF sensor signal is higher than the PCM expects for current operating conditions. The sensor is reporting too much airflow — typically because the sensor itself has failed, or a wiring short is pulling the signal voltage high. The most common cause is a failed MAF sensor (35%), followed by a wiring short to voltage (25%) and a restricted exhaust (15%). Unlike most MAF codes, cleaning the sensor is less likely to fix this one — high-input faults usually point to electrical failure.
Severity: Moderate
Safe to drive: Yes, short distances — engine will run rich
Repair cost: $5–$300 depending on cause
DIY difficulty: Easy to Moderate
What does P0103 mean?
The MAF sensor sends a signal to the PCM proportional to the mass of air entering the engine. P0103 sets when this signal exceeds the maximum expected value for current RPM and throttle position. The PCM is seeing an airflow reading that's impossibly high for what the engine is actually doing.
This is the opposite of P0102 (low input). While a dirty MAF typically under-reports airflow (low signal), P0103 indicates over-reporting — too much voltage or frequency on the MAF circuit. This causes the PCM to inject too much fuel, creating a rich condition.
The PCM may fall back to estimated airflow from throttle position and RPM data. You'll likely notice rich-running symptoms: black smoke from the exhaust, poor fuel economy, a fuel smell, and possible rough running.