P024D

What it means

P024D means the engine control unit has seen a signal from the charge air cooler bypass position sensor 'A' that is outside the expected range or does not match the commanded position of the bypass flap or valve. The circuit is not necessarily open or shorted, but the reported position does not make sense. It is only found on certain turbocharged engines, and the layout and sensor location vary by model and engine.

Symptoms

• Engine warning light on
• Loss of power or reduced boost, possibly with the car in limp mode
• Poor or hesitant acceleration
• Higher than usual intake air temperature or poor fuel economy
• Rough running or hesitation under load

Possible causes

• Bypass flap or valve sticking, seized or carbon-fouled so it cannot reach the commanded positionlikely
• Faulty bypass actuator or its position sensor giving an incorrect readinglikely
• Damaged wiring, poor connector contact or corrosion in the sensor circuit (signal, reference or earth)likely
• Loose, broken or disconnected linkage between the actuator and the flappossible
• Vacuum or pressure supply fault, where the actuator is vacuum or pneumatically operated (depends on the model)possible
• Low or unstable supply voltage or a poor earth affecting sensor readingspossible
• Faulty engine control unit or an outdated calibration, where the manufacturer has documented thisrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine load, coolant and intake air temperature when the fault set.
2. Check for related codes, such as boost, intake air temperature or actuator circuit faults, and deal with those in sequence.
3. Visually inspect the bypass actuator, linkage, wiring and connectors for damage, heat, oil, corrosion or loose fittings.
4. Check for any technical service bulletins or calibration updates for the specific vehicle and engine.
5. Use a scan tool with live data to compare the commanded and actual bypass position while operating the actuator, if the vehicle supports it.
6. Check the flap moves freely through its full range by hand or via the actuator test, and check for carbon build-up or a seized spindle.
7. Check the sensor supply, signal and earth with a multimeter against the manufacturer's specification, and test for voltage drop under load.
8. If the actuator is vacuum operated, check the vacuum supply, hoses and control solenoid for leaks and correct operation.

How to fix

• Clean or replace a sticking or seized bypass flap or valve assembly.
• Replace the bypass actuator or position sensor if it fails testing, then carry out any adaptation or relearn the manufacturer requires.
• Repair or replace damaged wiring and connectors, and clean or refit any poor terminals.
• Refit or replace broken or loose linkage and fixings.
• Repair vacuum or pneumatic supply faults found in the actuator control system.
• Update the engine control unit software only where an official update addresses this fault, or repair the control unit if testing proves it faulty.

Can I keep driving?

Nearby codes

• P024CGenericCharge Air Cooler Bypass Position Sensor A Circuit
• P024EGenericCharge Air Cooler Bypass Position Sensor A Circuit Low