P024A

What it means

P024A is the generic SAE J2012 code for Charge Air Cooler Bypass Control 'A' Range/Performance. The engine control unit has found that the charge air cooler bypass valve or actuator is not moving to, or holding, the commanded position, or that its position feedback does not match the command. Charge air cooler bypass systems are only fitted to certain turbocharged and supercharged engines, so the exact layout depends on the model and engine.

Symptoms

• Engine warning light on
• Reduced power or the car going into limp mode
• Hesitation or poor response under boost
• Higher than normal intake air temperatures or knock-related power loss
• Possible hissing or whistling from a boost or vacuum leak
• Slightly worse fuel economy

Possible causes

• Charge air cooler bypass valve or flap stuck, sooty or seizedlikely
• Faulty bypass actuator (electric motor or vacuum-operated)likely
• Damaged wiring, poor connector contact or corrosion in the actuator or position sensor circuitpossible
• Vacuum supply fault, split hose or faulty control solenoid (on vacuum-operated systems)possible
• Faulty position sensor or intake air temperature sensor giving implausible readingspossible
• Boost leak or restricted charge air cooler affecting the readings the ECU expectsrare
• Fault in the engine control unit or an outdated calibration, where the manufacturer has issued a known updaterare

How to diagnose

1. Read all stored and pending codes and freeze frame data to see the engine load, temperatures and speed when the fault set.
2. Check for other related codes such as boost, intake air temperature or actuator circuit faults, and deal with those first.
3. Visually inspect the bypass valve, actuator, linkage, wiring and connectors for damage, corrosion, oil, soot or loose fittings.
4. Inspect the charge air pipes, hoses and cooler for leaks, splits or oil contamination, and check vacuum lines if the system is vacuum-operated.
5. Using a scan tool with actuator tests, command the bypass valve and watch whether it moves smoothly and whether the reported position follows the command.
6. Check the actuator or solenoid supply, earth and signal circuits with a multimeter or oscilloscope against the manufacturer's data.
7. Check the vacuum supply and solenoid operation if fitted, following the model-specific procedure.
8. Compare intake air temperature sensor readings with other temperature sensors on a cold engine to check plausibility.

How to fix

• Clean or free off a sticking bypass valve if the manufacturer allows it, or replace the valve assembly if it is seized or damaged.
• Replace the bypass actuator if it fails the functional test.
• Repair damaged wiring or connectors, then clear the code and retest.
• Replace split vacuum hoses or a faulty control solenoid.
• Replace a faulty position or temperature sensor.
• Repair any boost leaks or a damaged charge air cooler, and apply a manufacturer calibration update only if one is known to address this fault.

Can I keep driving?

Nearby codes

• P0249GenericTurbocharger/Supercharger Wastegate Actuator B Low
• P024BGenericCharge Air Cooler Bypass Control A Stuck