OBD-II Code · Fuel & Air
P0100
Mass or Volume Air Flow Circuit
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$35–$450
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
MAF circuit fault — ECM not seeing coherent signal on the MAF signal wire.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Hesitation
- Stall
- Reduced power
- Check engine light
Likely causes
- Chafed harnessMost common
- Corroded connector
- Cracked solder joint in MAF
- Rodent damage
Read the full diagnostic procedureP0100 indicates an electrical fault in the Mass Air Flow sensor circuit itself — the ECM is not seeing a coherent signal on the MAF signal wire, dist…
P0100 indicates an electrical fault in the Mass Air Flow sensor circuit itself — the ECM is not seeing a coherent signal on the MAF signal wire, distinct from P0101 which says the signal is present but implausible.
Cheapest-first ladder
- unplug the MAF connector and inspect for green corrosion or pushed-back pins (5 minutes, free); back-probe the 5V reference with a DMM key-on engine-off and confirm 4.9-5.1V, then check the ground reference (should be under 0.1V drop to battery negative); with engine running at idle, the signal wire on a digital MAF should show a frequency between 2.0-4.5 kHz on a 2.4L four-cylinder and 3.5-6.0 kHz on a 5.7L V8, while an analog MAF idles around 0.7-1.1V and climbs to 4.0-4.5V at WOT; airflow at warm idle should read roughly 3-5 g/s on a 2.4L, 6-9 g/s on a 5.7L V8, and 25-35 g/s near WOT on the same V8.
- Do not throw a $250 MAF at a P0100 before you have ruled out a chafed harness against the valve cover or a corroded ECM pin — both are common and a new sensor will set the code again within minutes.
Vehicle-specific patterns2004-2008 Ford F-150 5.4L 3V routinely chafes the MAF harness where it crosses the passenger valve cover, setting P0100 intermittently after engine w…
- 2004-2008Ford F-150 5.4L 3V routinely chafes the MAF harness where it crosses the passenger valve cover, setting P0100 intermittently after engine warm-up;
- 2007-2014GM 5.3L trucks throw P0100 when the MAF connector locking tab breaks and the plug walks loose over speed bumps;
- 2003-2007Honda Accord/Odyssey J-series sees P0100 from a cracked solder joint inside the MAF itself, not a wiring fault, and the sensor must be replaced;
- 2008-2012VW/Audi 2.0T (BPY, CCTA) sees P0100 from rodent-chewed insulation under the engine cover where the MAF harness crosses the airbox.
Estimated repair$35 to $450.
Look up another code
P0100 — frequently asked
What does a P0100 code mean?
MAF circuit fault — ECM not seeing coherent signal on the MAF signal wire.
What causes a P0100 code?
Common causes: Chafed harness; Corroded connector; Cracked solder joint in MAF; Rodent damage.
What are the symptoms of a P0100 code?
Typical symptoms: Hesitation; Stall; Reduced power; Check engine light.
Is it safe to drive with a P0100 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $35-$450.
How do I diagnose a P0100 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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