P0101: Mass Air Flow (MAF) Sensor Circuit Range/Performance
Updated November 12, 2026
The mass airflow sensor tells the engine computer how much air is coming in. P0101 means its reading doesn't make sense compared with what the computer expects from throttle position, engine speed and load.
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🔧 Want to check this yourself? An OBD2 scanner reads the code; models with live data also show the sensor readings used in the checks below. See code readers and scanners from $24.99 ↓ · Which scanner do I need?
Common causes
- A dirty MAF sensor element (oil from aftermarket air filters is a common culprit)
- An air leak between the MAF sensor and the throttle body
- A clogged air filter or a restricted intake
- A failing MAF sensor or a wiring problem
Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.
Symptoms
- Check engine light
- Hesitation, stalling or rough idle
- Poor fuel economy
- Sometimes lean or rich codes alongside it
Is it safe to drive?
Usually drivable, but poor air readings can cause stalling or hesitation in traffic, so fix it soon.
How to check it with a scanner
- Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
- Inspect the air filter and the intake duct for cracks or loose clamps after the sensor.
- Clean the sensor with MAF cleaner only (never touch the element).
- Watch MAF grams-per-second readings in live data at idle and as RPM rises; they should climb smoothly.
- After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.
A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.
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Questions
What does P0101 mean?
P0101 is the generic OBD2 code for "Mass Air Flow (MAF) Sensor Circuit Range/Performance." The mass airflow sensor tells the engine computer how much air is coming in. P0101 means its reading doesn't make sense compared with what the computer expects from throttle position, engine speed and load.
Is it safe to drive with P0101?
Usually drivable, but poor air readings can cause stalling or hesitation in traffic, so fix it soon.
How do I check P0101 myself?
Read the code and freeze-frame data with an OBD2 scanner, then: Inspect the air filter and the intake duct for cracks or loose clamps after the sensor. Clean the sensor with MAF cleaner only (never touch the element). Watch MAF grams-per-second readings in live data at idle and as RPM rises; they should climb smoothly.
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