Generic fault code

P009A — Correlation fault between intake air temperature and ambient air temperature

Q: What usually causes code P009A?

Faulty, aged or drifting sensor. The most likely causes come first. Only a check on the car confirms which one is yours.

Q: What are the symptoms of code P009A?

Jerking or lack of power. Rough idle or stalling. Higher fuel use and, on diesels, black smoke. These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.

The control unit stores code P009A when it detects this fault: “Correlation fault between intake air temperature and ambient air temperature”.

Indicative severity: LowFuel and air metering

Updated on October 13, 2026

Reviewed by Daniel Morales, founder of Reprorace SL, on October 13, 2026

What does code P009A mean?

The engine measures the incoming air and meters the fuel so the mixture is right; the throttle, the accelerator pedal and the turbo are here too. A fault usually shows as higher fuel use, jerking, lack of power or hard starting.

System: P · Powertrain
Area: Fuel and air metering · Car system: Fuel and air
Type: Generic (SAE J2012 / ISO 15031-6): the same meaning on every make
Indicative severity: Low. Check at the next service; usually does not affect safety or driveability.

What usually causes code P009A?

Faulty, aged or drifting sensor

The most likely causes come first. Only a check on the car confirms which one is yours.

What are the symptoms of code P009A?

Jerking or lack of power
Rough idle or stalling
Higher fuel use and, on diesels, black smoke

These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.

Can I keep driving with code P009A?

Usually yes, with care. This kind of fault does not usually affect safety or how the car drives, but have it checked at the next service. If you notice anything different (jerking, noises, smells, smoke or a red warning light), stop somewhere safe and get advice.

This is guidance only: only someone who checks the car can say whether it is safe to drive.

An indicative description of the code's generic meaning. Each manufacturer may give it a different meaning, conditions or tests: always follow its service information and your workshop's advice.

What you can do yourself

For this kind of fault

Check that the air filter is clean and that the duct between the filter and the engine has no cracks or loose clamps. Do not clean the air flow sensor with products not made for it.

Read the code and keep the report: with an ECO-LITE in the OBD socket you see it on your phone or computer, with the data captured when the fault happened.
Look for anything obvious: a loose connector, a disconnected hose, a fuel cap not closed properly or a low fluid level. Do not take apart anything you do not know.
Clear the code only after writing it down or after the repair. Clearing turns the light off, but it also deletes the freeze-frame data and the readiness monitors used at the inspection.
Drive normally for a few days and read the codes again. If the code comes back, the fault is still there: book the workshop and bring the report.

Read your car's fault codes on your phone

With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.

See the ECO-LITE Reserve (presale)

Related codes

P0095Intake air temperature sensor 2 (bank 1), circuit: malfunction
P0096Intake air temperature sensor 2 (bank 1), circuit: range/performance
P0097Intake air temperature sensor 2 (bank 1), circuit: signal low
P0098Intake air temperature sensor 2 (bank 1), circuit: signal high
P0099Intake air temperature sensor 2 (bank 1), circuit: intermittent/erratic
P00A5Intake air temperature sensor 2 (bank 2), circuit: malfunction

P00xx codes: fuel and air metering and auxiliary emission controls

All fault codes