P0100 Mass or Volume Air Flow Circuit
P0100 is a generic OBD2 powertrain code. It means “Mass or Volume Air Flow Circuit” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0100 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P01xx
- Urgency
- Moderate
What P0100 means
The mass air flow (MAF) sensor measures the air entering the engine, and every fuel injection is sized from it. The computer found its signal implausible for the engine’s speed and load (P0101), too low (P0102), too high (P0103), or a fault in its circuit (P0100).
Symptoms
- Hesitation or flat spots on acceleration
- A rough idle, or stalling just after starting
- Worse fuel economy
- Lean or rich codes appearing alongside
Most likely causes
- A dirty sensor element — oil from an over-oiled aftermarket air filter is the classic
- An air leak between the sensor and the throttle, such as a cracked intake boot
- A clogged air filter
- A damaged connector or wiring (especially behind P0102/P0103)
- A failed sensor
What to check first
- Inspect the air filter and the intake duct for cracks
- Clean the sensor with MAF cleaner — never wipe the element
- Check the connector and the wiring
- Compare the airflow reading at idle with a known-good value for your engine before buying a sensor
Can I keep driving with P0100?
Drivable — plan the repair soon
Yes, but don’t put it off for long: the computer is estimating the airflow instead of measuring it, so the engine runs less smoothly, uses more fuel, and a lean or rich condition can follow.
What the wording tells you
The wording names a fault in the component’s circuit without saying more. Check the connector, the wiring and the fuse, and test the component, before replacing it.
How P0100 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Fuel & air metering.
The specific fault within this range.
Where to look: Fuel & air metering
The sensors the engine computer meters fuel from — mass air flow, manifold pressure, intake air and coolant temperature, throttle position, oxygen sensors and fuel pressure — the fuel trims it learns from them, and the injector, fuel-pump and turbocharger circuits.
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Read and clear P0100 on your iPhone
Brimly reads stored, pending and permanent codes through a Bluetooth LE or Wi-Fi OBD2 adapter, explains each one offline from the same 2,693-code dictionary as this page, and clears them once the fault is fixed — each clear goes into the car’s service history with the codes it removed. OBD diagnostics are part of Brimly Forever, a one-time purchase; the PRO assistant explains a code for your exact car.
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Frequently asked
What does P0100 mean?
P0100 is a generic OBD2 powertrain code. It means “Mass or Volume Air Flow Circuit” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The mass air flow (MAF) sensor measures the air entering the engine, and every fuel injection is sized from it. The computer found its signal implausible for the engine’s speed and load (P0101), too low (P0102), too high (P0103), or a fault in its circuit (P0100).
Can I drive with P0100?
Yes, but don’t put it off for long: the computer is estimating the airflow instead of measuring it, so the engine runs less smoothly, uses more fuel, and a lean or rich condition can follow.
What causes P0100?
A dirty sensor element — oil from an over-oiled aftermarket air filter is the classic; An air leak between the sensor and the throttle, such as a cracked intake boot; A clogged air filter; A damaged connector or wiring (especially behind P0102/P0103); A failed sensor.
How do I clear P0100?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0100 the same on every car?
Yes. P0100 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.