P0102: Air flow sensor circuit low input

What P0102 means

The air flow sensor sends a voltage (or frequency) that rises with the amount of air coming in. If the ECU sees it below what is possible, it treats the circuit as faulty and stores this code. It can also appear if very little air gets in through a blocked filter or duct, but an electrical problem is more usual.

Most common causes

• Loose, corroded or poorly seated sensor connector
• Signal or power wire broken, or chafed and touching earth
• A faulty air flow sensor
• No power to the sensor (fuse or relay)
• Badly blocked air intake or filter

Symptoms

• Engine warning light on
• Loss of power, sometimes with limp mode
• Unstable idle or stalling when you lift off
• Slightly harder starting

Can you drive with P0102?

With care You can drive, but the engine runs on backup values and may feel flat or stall at idle. Get it fixed soon.

How to check it

At idle, watch air flow in live data: if it reads close to zero, switch off, unplug and refit the connector, then try again. If nothing changes, have the garage check the sensor’s power supply.

How to read and clear P0102 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0102 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0100 Mass or volume air flow sensor circuit fault
• P0101 Air flow sensor range or performance problem
• P0103 Air flow sensor circuit high input
• P0104 Air flow sensor circuit intermittent
• P0105 Manifold absolute pressure (MAP) sensor circuit fault
• P0106 Manifold absolute pressure (MAP) sensor range or performance
• P0107 Manifold absolute pressure (MAP) sensor circuit low
• P0108 Manifold absolute pressure (MAP) sensor circuit high
• P0109 Manifold absolute pressure (MAP) sensor circuit intermittent
• P0110 Intake air temperature sensor circuit fault

P0102 is a generic code, so it means the same on any make, for example on BMW, Citroën, Ford, Mercedes-Benz, Renault, Volvo. See what Final OBD does on your car in makes and models.