Fuel and air

P0103 — Mass Air Flow (MAF) Sensor Circuit High Input

Severity: medium Drive with care, to a shop

What P0103 means

The engine control unit constantly compares the mass air flow (MAF) sensor signal with what it expects for the current engine speed and throttle position. P0103 is stored when the sensor's voltage or frequency is above the allowed range. The airflow reading is then too high or unreliable, so fuel delivery is calculated incorrectly.

Symptoms

  • Check Engine light on
  • Rough or unstable idle
  • Hard starting or stalling
  • Poor fuel economy
  • Rich running with black exhaust smoke
  • Hesitation or weak throttle response

Possible causes

  1. Failed MAF sensor
  2. Dirty MAF sensor, including oil contamination from an over-oiled reusable air filter
  3. Open, corroded or loose wiring or connector
  4. Signal wire shorted to power
  5. Air leak in the intake after the MAF sensor
  6. Rarely, a faulty PCM or software problem

How to diagnose

  1. Scan for codes and freeze frame data and look for other intake or fuel trim codes
  2. Inspect the air filter, intake duct and MAF sensor for dirt, oil or damage
  3. Check the connector and harness for corrosion, chafing, bent pins or a short to power
  4. Compare MAF readings at idle and under load with expected values for the engine
  5. Review short-term and long-term fuel trims
  6. Inspect the intake path after the sensor for cracks and leaks
  7. Check sensor power, ground and signal at the connector with a multimeter
  8. If the sensor and wiring are good, test the PCM

Common fixes

  • Clean the MAF sensor with a dedicated MAF cleaner
  • Replace the faulty MAF sensor
  • Repair or replace damaged wiring or connectors
  • Seal intake air leaks
  • Reprogram or replace the PCM (rare)

Questions and answers

Can I drive with a P0103 code?

Short trips are usually possible, but the engine may run rough or stall. Fix the cause soon to avoid wasted fuel and extra stress on the catalytic converter.

Will cleaning the MAF sensor fix P0103?

If contamination is the cause, cleaning with a dedicated MAF cleaner may help. If the sensor has failed or the wiring is damaged, you will need to replace the sensor or repair the harness.

Can a vacuum leak cause P0103?

It can, but leaks more often set lean-condition codes. Still, rule out cracks in the intake after the sensor during diagnosis.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.