Mass Air Flow Circuit High Input
The P0103 code means the vehicle's onboard diagnostic system has detected: Mass Air Flow Circuit High Input. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $50-$200 for MAF sensor
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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
-
Monitor MAF sensor voltage. High signal at idle (above 2.5V on analog sensors) confirms the issue.
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Check wiring for shorts to the 5V reference or 12V supply lines.
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If an aftermarket intake was recently installed, verify it is compatible with the factory MAF sensor.
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Compare MAF reading to expected value from a factory data chart at the current RPM.
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Substitute a known-good sensor to verify.
Common Fixes by Vehicle
What techs usually find when diagnosing P0103 on specific vehicles — tap your vehicle for the fix and the exact part:
2009-2020 Chevrolet Silverado/GMC Sierra 5.3L Easy DIY
MAF sensor circuit high input. The MAF is reading higher airflow than expected. Check for a contaminated MAF element from oil-soaked aftermarket air filters. Replace with a dry paper filter and clean the MAF with CRC MAF cleaner. If the MAF sensor is reading above 5V, the internal circuit has failed -- replace with ACDelco 213-4222.
Labor: 10-20 min2002-2015 Nissan Altima/Pathfinder 2.5L/3.5L Easy DIY
High MAF signal can be caused by a contaminated sensor element or an electrical short in the wiring. Check the MAF connector for corrosion and bent pins. If the signal voltage stays above 4.5V at idle, the sensor has failed internally. Replace with Hitachi MAF0031. Also check for a restricted air filter causing turbulent airflow over the sensor element.
Labor: 10-20 min2009-2020 Ford F-150/Expedition 5.0L Easy DIY
MAF reading too high on the 5.0L Coyote usually indicates a failed MAF sensor element or water intrusion into the MAF connector. Check the air filter box drain and ensure the air box is sealed properly. If the engine runs rich (black smoke), the MAF is over-reporting and needs replacement (Motorcraft DY-1350). Clean first with CRC MAF cleaner.
Labor: 10-20 minFrequently 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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0103 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
See All Codes & Fixes for Your Vehicle
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