Mass Air Flow Circuit Low Input
The P0102 code means the vehicle's onboard diagnostic system has detected: Mass Air Flow Circuit Low 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
- Poor acceleration
- Engine runs lean
- Rough idle
- Fuel economy drops
Probable Causes (Ranked by Likelihood)
- Faulty MAF sensor producing low voltage Very High
- Open circuit or poor ground in MAF wiring High
- Contaminated MAF sensor element Moderate
- Air filter severely clogged Moderate
- Wiring short to ground Low
Step-by-Step Diagnostic Procedure
-
Check MAF signal voltage at idle (typically 0.5-1.5V for analog sensors). Below 0.3V indicates a short.
-
Inspect wiring from MAF sensor to PCM for damage, corrosion, or breaks.
-
Verify the MAF sensor has proper power and ground at the connector (key on): hot-wire MAF sensors are fed by a 12V ignition/battery supply, so confirm ~10.5V or more on the power pin (a blown MAF fuse or open power feed is a common cause of a circuit-low signal). On sensors that also use a 5V reference pin, confirm that too, plus a clean ground.
-
Clean the MAF sensor and retest.
-
Temporarily substitute a known-good MAF sensor to confirm diagnosis.
Common Fixes by Vehicle
What techs usually find when diagnosing P0102 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 low input. Clean the MAF sensor with CRC MAF cleaner first. On GM trucks with aftermarket oiled air filters (K&N), oil contaminates the MAF hot wire element. Switch back to a dry paper filter. If the MAF element is damaged, replace with ACDelco 213-4222. Also check for a torn intake air duct between the filter and MAF.
Labor: 10-20 min2002-2015 Nissan Altima/Sentra 2.5L QR25DE Easy DIY
MAF signal is too low -- usually a dirty or failed sensor element. Clean with CRC MAF cleaner. If the code persists, check for a large air leak in the intake boot after the MAF that allows unmetered air in, diluting the MAF reading. Replace the MAF sensor (Hitachi MAF0031) if cleaning does not resolve it. Inspect the air filter for debris that may have damaged the element.
Labor: 10-20 min2009-2020 Ford F-150/Explorer 3.5L EcoBoost Easy DIY
Low MAF signal on EcoBoost often indicates a boost leak at the charge pipe causing the MAF to read lower than expected airflow. Check all turbo piping connections and the intercooler hoses for leaks. The plastic charge pipe cracks under boost -- Ford TSB 14-0191. Clean the MAF first, then smoke test the intake tract if code returns.
Labor: 10 min (clean), 1 hour (boost leak)2004-2017 Volkswagen Jetta/Passat 2.0T TSI Easy DIY
MAF sensor underreporting airflow on VW turbo engines. Check for boost leaks at the diverter valve and intercooler piping first. The diverter valve diaphragm tears and leaks boost. Clean the MAF with CRC MAF cleaner. Replace with Bosch 0280218259 if cleaning fails. Also check the PCV valve for a torn diaphragm causing a vacuum leak.
Labor: 10-30 minFrequently Asked Questions
Will P0102 cause my car to run rich or lean?
A low MAF signal tells the ECU less air is entering than actual. The ECU reduces fuel delivery, resulting in a lean condition. This can trigger P0171 or P0174 fuel trim codes as well.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0102 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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