Mass Air Flow Circuit Malfunction
The P0100 code means the vehicle's onboard diagnostic system has detected: Mass Air Flow Circuit Malfunction. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $50-$200 for MAF sensor; $0 for cleaning
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Common Symptoms
- Check Engine Light on
- Engine stalls
- Hesitation on acceleration
- Rich or lean running
- Hard starting
Probable Causes (Ranked by Likelihood)
- Faulty MAF sensor Very High
- Wiring damage or poor connector at MAF High
- Air leak between MAF and throttle body Moderate
- Contaminated MAF sensing element Moderate
- PCM fault Low
Step-by-Step Diagnostic Procedure
-
Check MAF sensor wiring and connector for corrosion, bent pins, or chafing.
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With engine running, monitor MAF g/s reading. At idle, a 4-cylinder should show 2-7 g/s. Erratic or zero readings indicate sensor failure.
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Clean the MAF sensor with dedicated MAF cleaner spray and retest.
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Check for air leaks in the intake boot between MAF and throttle body.
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Compare actual vs. calculated MAF with a scan tool at various throttle positions.
Common Fixes by Vehicle
What techs usually find when diagnosing P0100 on specific vehicles — tap your vehicle for the fix and the exact part:
2005-2014 Ford F-150/Explorer 4.6L/5.4L/3.5L EcoBoost Easy DIY
MAF sensor circuit malfunction typically caused by an oiled-over hot wire (from over-oiled aftermarket air filter) or a cracked intake boot pulling unmetered air. Clean MAF with CRC MAF-specific cleaner, replace the air filter with OE paper filter, and inspect the intake boot for cracks near the clamps.
Labor: 15-30 min2003-2015 GM 5.3L/6.0L Vortec (Silverado, Tahoe, Express) Easy DIY
MAF sensor circuit fault almost always cleaned up by replacing with an ACDelco OEM MAF (part number 213-3766). Aftermarket MAFs fail quickly on LS-series engines. Also verify air-filter housing has no vacuum leaks at the lid gasket.
Labor: 15 min2000-2010 Toyota Camry/Corolla/Tacoma 2.4L/2.7L Easy DIY
Toyota MAF/IAT combo sensor circuit fault — clean with MAF-safe cleaner first. If cleaning doesn't resolve, replace with Denso OEM unit. Toyota MAFs are particularly sensitive to oiled K&N-style filters — revert to a paper filter.
Labor: 15-30 minFrequently Asked Questions
Can I clean a MAF sensor instead of replacing it?
Yes, and it often works if contamination is the cause. Use only dedicated MAF cleaner. Do not touch the sensing wire and allow it to dry completely before reinstalling.
What happens if I drive with a bad MAF sensor?
The ECU will use a fallback fuel map, which causes poor fuel economy, rough running, and may damage the catalytic converter over time.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0100 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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