P024B
Charge Air Cooler Bypass Control A StuckP024B is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Bypass Control A Stuck. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P024B means
Code P024B is stored when the Engine Control Module (ECM) determines that the charge air cooler (intercooler) bypass valve designated "A" is physically stuck and can no longer be controlled electronically. Unlike P024A, which indicates out-of-range performance, P024B means the valve has ceased responding to commands entirely — it is frozen in either the open or closed position. The ECM commands valve movement and monitors actuator feedback; when no movement is detected across multiple command attempts, P024B is stored. A valve stuck open keeps intake air permanently bypassing the intercooler, causing elevated charge temperatures, increased knock risk, and power loss. A valve stuck closed prevents the bypass function during cold starts, prolonging warm-up and increasing emissions. In either case, because the ECM cannot trust the bypass valve, it may disable the forced-induction system's boost targets or enter a reduced-power mode to protect the engine. Mechanical obstruction is the most common cause, but electrical faults and actuator failures can produce the same result.
Common causes
Most-frequently reported root causes when P024B is logged.
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1
Bypass valve physically jammed by debris, ice, or carbon deposits
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2
Seized bypass valve actuator motor due to corrosion or mechanical failure
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3
Damaged wiring harness causing a complete open or short circuit to the actuator
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4
Blown fuse or failed relay preventing power from reaching the bypass actuator
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5
Corroded or broken connector pins at the bypass valve harness connector
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6
Broken linkage or mechanical component in the valve assembly
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7
ECM internal failure causing the relay control driver to stop functioning
Symptoms drivers notice
How to diagnose P024B
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and attempt to command the bypass valve open and closed using the actuator test; confirm whether any mechanical response is observed
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2
Locate the bypass valve in the charge air piping and inspect for visible damage, ice, or foreign material jamming the valve
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3
Remove the valve and physically check its range of motion; clean out any deposits or debris and verify free movement before reinstalling
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4
Inspect the wiring harness for cuts, breaks, or corrosion; check fuses and the control relay for continuity and correct operation
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5
Use a multimeter to verify reference voltage, ground, and signal integrity at the actuator connector with the key on
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6
After mechanical and electrical repairs, clear codes and retest using the scan tool actuator test to confirm the valve moves through its full range
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7
If the valve and circuits are confirmed serviceable but the code returns, inspect ECM connector pins and consult TSBs before replacing the ECM
Related powertrain codes
Frequently asked questions
Is P024B more serious than P024A?
Generally yes. P024B means the valve has stopped responding entirely, which is more disruptive to engine management than the out-of-range performance issue indicated by P024A. Limp mode activation is more likely with P024B.
Can the stuck valve cause engine damage?
A valve stuck open permanently routes hot compressed air past the intercooler, raising charge temperatures and increasing knock risk on turbocharged engines. Prolonged operation in this state can lead to detonation damage, so prompt repair is recommended.
Can cold weather cause P024B?
Yes. In very cold climates, moisture can freeze inside the bypass valve housing and jam the valve in position. If the code appears only in winter and clears once the engine warms up, ice obstruction is a likely cause.
Do I need to replace the whole bypass valve assembly or just the actuator?
It depends on the fault. If the valve plate and housing are clean and move freely but the actuator motor does not respond, replacing only the actuator may be sufficient. If the valve body is corroded or cracked, the full assembly should be replaced.
Disabling P024B in software
RaceTune can permanently disable P024B — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECU families we can disable P024B on
We hold the DaVinci A2L disable definitions for these families, so the exact P024B path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.
- Bosch EDC17CP44 verified
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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