P0102 fault code: mass air flow sensor signal too low
Plain-language definition
Mass or Volume Air Flow Sensor A Circuit Low
What does it mean?
The mass air flow sensor (MAF) measures how much air goes into the engine and reports it to the engine computer as an electrical signal. Depending on the type of sensor, this signal may be a voltage or a frequency; as air flow increases, the value rises too.
P0102 is stored when the signal stays lower than it should be for the engine's operating conditions; the engine computer gets a value from the sensor as if very little air were going into the engine. This is usually an electrical problem: a loose or broken connection, a problem in the supply line, or a faulty sensor.
When the engine computer can't get reliable air data, it usually switches to working with estimated values. You may notice the engine being hard to start, stalling at idle, misfiring when accelerating or losing power; on diesel cars there may also be black smoke.
How serious is it?
It's a Warning-level code. Because the engine computer has to calculate the amount of air from estimated values, how the engine runs and fuel consumption can be affected.
Severity is a guide; if the warning light is flashing or you notice symptoms while driving, have the car checked at a workshop.
Common general causes
- A sensor connector that is loose, unplugged or corroded
- A break in the sensor wiring, or a short to ground
- A faulty mass air flow sensor
- A problem with the sensor's supply voltage or ground line
- A large air leak after the sensor (e.g. an intake hose that has come loose)
- Less often, problems coming from the engine computer (ECU)
The list shows general causes; a workshop finds the actual cause on your car with a check.
Definitions by make
Some manufacturers record the same code under their own wording:
- Audi, GM, Seat, Skoda, Volkswagen
- Mass Air Flow (MAF) Sensor Circuit Low Frequency
Related codes
How does it appear in the 2dakika report?
Mass or Volume Air Flow Sensor A Circuit Low
If the code is read as a confirmed (stored) fault, the report shows it with the "Warning" severity; in pending or past records, codes that don't request the warning light and aren't critical appear as "Info". If the engine computer stored them, the conditions when the fault was recorded (engine temperature, rpm, speed) are shown too.
Read this code with the OBD-X1, and clear it from the app after the repair.
Clearing the code doesn't fix the fault; if the problem persists, the code comes back.