Meaning
The voltage or frequency from the flowmeter is below the lower limit. The computer does not trust the sensor and starts to calculate the air based on other data.
Urgency
Low to medium. The car is driven, but often with less power, higher consumption or emergency mode.
It affects
Gasoline and diesel engines with flow meter. Sensor, coupling, wiring, power supply.
What does P0102 mean
The flow meter measures how much air enters the engine. With the P0102 the signal is so low that the computer takes it to be a fault in the circuit rather than just an inaccurate measurement. The inaccurate measurement is P0101, and the too high signal — P0103.
Symptoms
- Lamp "Check Engine"
- Low power, emergency mode (especially on diesels)
- Rough idle or stalls on throttle
- Higher consumption, black smoke with diesel
| Can it be driven?
Yes. Most cars drive normally in reserve mode, but the consumption goes up. Remove the cause soon.
Common reasons
- Pulled out, oxidized or broken coupling — often after changing the air filter.
- Broken or frayed wire — signal, mass or power supply.
- Faulty flow meter.
- Large air leak after flow meter — dropped cuff (see P0171).
How we diagnose it
- We look at the clutch, sleeves and air box.
- We measure the power supply, ground and sensor signal with a multimeter or oscilloscope.
- We compare the reported air with volume and rpm expectations.
- We replace the flow meter only if the wiring is fine.