P24F2: Exhaust Gas Recirculation Temperature/Charge Air Cooler Temperature Correlation
What to do
Ask for the car to be left overnight if diagnosis is not immediately obvious. These faults are found most reliably from stone cold, when all the temperature sensors should agree with each other — a road test tells you much less.
Mention any loss of power or a whistling noise under acceleration. That would point at a leaking charge air cooler or a loose hose, which causes this code mechanically rather than electrically and is a different repair.
Ask whether the EGR valve has been checked. A valve that is not closing fully heats the intake for real, so both sensors are correct and the valve is the fault — replacing a sensor in that situation fixes nothing.
What this code means
The exhaust gas recirculation temperature and the charge air cooler temperature disagree by more than the module allows.
These two sensors measure different things that have to add up. Recirculated exhaust gas and cooled intake air mix before entering the cylinders, so their temperatures constrain each other. When the module knows both, it can predict the mixture's temperature — and when the two readings cannot both be true, it says so.
Like every correlation code, this names a disagreement rather than a culprit. Either sensor may be the wrong one, and identifying which needs both compared under a known condition.
A cold soak settles it cheaply and reliably. After the vehicle has stood overnight, every temperature sensor on it should read close to ambient and close to each other — coolant, intake air, EGR, charge air. The one that disagrees at that moment is the one that has drifted, and no road test is needed to prove it.
This code has a genuinely mechanical cause worth checking before any sensor is replaced: a stuck EGR valve. A valve leaking hot gas when it should be closed heats the intake charge for real, so both sensors are telling the truth and the disagreement is the fault.
Charge air cooler leaks produce the mirror image. A split intercooler or a loose hose lets the charge run at a temperature that does not match what the EGR side implies.
Likely causes
Start here
- Sensor drifted out of calibration · moderate
- EGR valve stuck open · moderate
Less common
- Leaking charge air cooler or hose · moderate
- High resistance in sensor wiring · moderate
- Carbon build-up in the EGR system · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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