P0103 serious

Mass Air Flow Circuit High Input

What does P0103 mean?

The P0103 code means the vehicle's onboard diagnostic system has detected: Mass Air Flow Circuit High Input. This is a serious severity code.

Common Symptoms

  • Check Engine Light on
  • Rich running or black smoke
  • Poor fuel economy
  • Rough idle
  • Possible engine flooding

Probable Causes (Ranked by Likelihood)

  • Faulty MAF sensor producing high voltage Very High
  • Short to voltage in MAF signal wire High
  • Modified air intake causing sensor over-read Moderate
  • PCM input circuit fault Low

Step-by-Step Diagnostic Procedure

  1. Monitor MAF sensor voltage. High signal at idle (above 2.5V on analog sensors) confirms the issue.

  2. Check wiring for shorts to the 5V reference or 12V supply lines.

  3. If an aftermarket intake was recently installed, verify it is compatible with the factory MAF sensor.

  4. Compare MAF reading to expected value from a factory data chart at the current RPM.

  5. Substitute a known-good sensor to verify.

Frequently Asked Questions

Can an aftermarket intake cause P0103?

Yes. Cold-air intakes that relocate or change airflow dynamics can cause the MAF to over-read. Some require a tune or MAF recalibration to function correctly.

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