Fuel and air

P024B — Charge Air Cooler Bypass Stuck (Circuit 'A')

Severity: medium Drive with care, to a shop

What P024B means

P024B means the engine control module does not see the charge air cooler bypass valve moving to the commanded position. This valve normally routes charge air through or around the intercooler to manage intake temperature and condensation. When the ECM sees that the valve is stuck, it stores the code.

Symptoms

  • Check Engine light on
  • Reduced power or limp mode
  • Sluggish acceleration or turbo lag
  • Worse fuel economy
  • Uneven performance under load

Possible causes

  1. Stuck or seized bypass valve (carbon, dirt, corrosion)
  2. Failed bypass valve actuator or solenoid
  3. Damaged wiring or corroded connector
  4. Open or shorted control circuit
  5. Missing vacuum or leaking vacuum line on vacuum-operated actuators
  6. Faulty ECM (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, then clear P024B and see if it returns.
  2. Inspect the bypass valve, ducts and actuator for dirt, oil, cracks or damage.
  3. Check that the valve moves freely, following the service procedure.
  4. Inspect the actuator connector and harness for corrosion, chafing and loose pins.
  5. Test power, ground and the control signal at the actuator connector.
  6. Command the actuator with a scan tool and confirm the valve moves and feedback changes.
  7. On vacuum actuators, check hoses, the vacuum solenoid and leaks.

Common fixes

  • Clean and free the stuck bypass valve
  • Replace the actuator or solenoid
  • Repair damaged wiring or connectors
  • Replace the whole bypass valve assembly if worn
  • Update software or replace the ECM (rare)

Questions and answers

What does P024B mean?

It is a charge air cooler bypass control fault: the ECM sees that the valve is not moving as commanded. The valve, its actuator or the wiring is usually to blame.

Can I drive with P024B?

For a short time, yes, but power may be limited and the engine works harder. Have it diagnosed soon.

How do I fix P024B?

Inspect the valve and wiring first, and clean any stuck valve. If the actuator does not respond, replace it.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.