StopOrDrive

Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0101 Mass airflow (MAF) sensor range or performance

Can I drive with P0101?

Drive with caution

Stop if the engine stalls, hesitates or won't restart.

A wrong airflow reading makes the engine computer mix fuel badly, which can cause hesitation, stalling at stops, and poor fuel economy. Most cars stay drivable, but avoid merging into fast traffic until it is fixed.

What does P0101 mean?

The sensor that measures how much air enters the engine is reporting numbers that do not make sense for current conditions. The computer compares the reading with throttle position and engine speed and sets P0101 when they disagree. The MAF sits in the intake duct after the air filter.

What causes P0101?

A dirty sensor or an air leak in the intake duct causes most cases, so check those before buying a new sensor.

  1. Dirty MAF sensor
  2. Air leak between the MAF and throttle body
  3. Clogged or badly fitted air filter
  4. Failed MAF sensor
  5. Oiled aftermarket air filter contaminating the sensor

How much does it cost to fix P0101?

$10 – $450

MAF cleaner spray: $10–$15 if you do it yourself. New sensor: $150–$450 installed. Use only cleaner made for MAF sensors, never touch the sensing wires, and let it dry fully before reconnecting. Check the duct clamps and the air filter too.

What are the symptoms of P0101, and how can I confirm it?

Hesitation when accelerating, rough idle, stalling, and poor fuel economy are common. Inspect the intake duct for cracks and loose clamps, then clean the sensor. On a scan tool, most engines read about 2 to 7 grams per second at warm idle. P0171 or P0172 may appear with it.

Will P0101 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on. After cleaning or replacing the sensor, clear the code; the computer relearns its fuel settings over a few drives. If P0101 returns soon, look for an intake air leak or a wiring problem before replacing the sensor.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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