Intake Air Temperature Too High

Possible causes

• CommonBlocked, leaking or oil-fouled intercooler on a turbocharged engine
• CommonHot air being drawn from inside the engine bay because ducting is missing or displaced
• CommonFailed intake air temperature sensor reading high
• PossibleHeat soak after idling in traffic on a hot day - sometimes the code is simply true
• PossibleCooling system fault raising under-bonnet temperature
• PossibleExhaust leak close to the intake, or a failed heat shield

What you might notice

• Loss of power, especially in hot weather or after sitting in traffic
• Pinging or knocking under load
• Poor fuel economy
• Check engine light on

What to check, in order

1. Check that the air intake ducting is complete and properly seated. A duct that has popped off leaves the engine breathing engine-bay air, and this code is often the only sign.
2. Compare intake air temperature against ambient with the engine cold and standing overnight. They should be within a few degrees; a large gap on a cold engine condemns the sensor.
3. On a turbocharged engine, inspect the intercooler and its pipework. A blocked core or an oily internal film both cut its ability to shed heat, and a split pipe lets hot charge air escape before it is cooled.
4. Check the cooling system as well. An engine running hot heats everything under the bonnet, including the air on its way in.
5. Read the codes for knock. This condition causes detonation, and a knock code stored alongside tells you it is already happening rather than merely likely.