P022F

Charge Air Cooler Bypass Control B Circuit High

P022F is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Bypass Control B Circuit High. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P022F
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P022F means

P022F is set when the ECM detects a higher-than-expected voltage or current signal in the charge air cooler bypass control "B" circuit. As the high-circuit counterpart to P022E, this code indicates that the "B" bypass control signal is reading above the calibrated upper threshold rather than below it. On turbocharged and supercharged engines, the charge air cooler bypass valve is modulated by the ECM to control whether compressed intake air passes through the intercooler or is diverted around it, affecting charge temperature and boost response. A high-circuit fault on the "B" circuit most commonly results from a short to battery voltage somewhere in the control wiring, which forces the ECM to detect a continuously energised signal regardless of its commanded output. This can cause the bypass valve to be held in one extreme position — either fully open or fully bypassed — depending on whether the valve is normally open or normally closed. An ECM output driver failure that saturates the control output high is another, rarer cause. The consequences mirror those of P022C on the "A" circuit: the ECM loses authority over charge-air thermal management on the "B" side, triggering a power-derate or limp strategy. Additionally, a sustained high-side fault risks overheating the bypass solenoid coil if it is held energised beyond its rated thermal capacity, potentially causing secondary coil damage.

Common causes

Most-frequently reported root causes when P022F is logged.

  • 1
    Short to battery voltage (B+) in the "B" bypass control circuit wiring or at the connector, forcing the signal line permanently above the expected threshold
  • 2
    Internal short within the bypass "B" actuator solenoid coil creating an unintended high-voltage feedback path
  • 3
    Chafed wiring insulation contacting an adjacent live circuit or battery positive terminal routing near the bypass harness
  • 4
    Damaged or bridged connector pins providing an unintended high-side voltage path to the signal wire
  • 5
    Defective relay in the bypass "B" supply circuit with welded contacts that hold the circuit continuously energised
  • 6
    Bypass valve actuator held continuously energised beyond its thermal limit, causing progressive coil degradation and abnormal circuit characteristics
  • 7
    ECM internal driver fault locking the "B" bypass control output in a permanently high state (rare; only suspect after all external causes are ruled out)

Symptoms drivers notice

MIL (Check Engine Light) illuminated with P022F stored, often appearing with other boost management or intercooler-related fault codes
Reduced engine power with a fixed or uncontrolled charge-air bypass condition preventing normal intercooler efficiency management
Vehicle entering limp mode or power-derate as the ECM implements a protective strategy when "B" bypass control authority is lost
Possible bypass actuator overheating if a short to voltage holds the solenoid coil continuously energised above its duty cycle rating
Rough running or misfiring caused by charge-air temperature deviations affecting the fuelling and ignition model
Intermittent drivability complaints that worsen with heat — thermal expansion aggravating a chafe fault or marginal connector bridge

How to diagnose P022F

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool, log all active and pending DTCs with freeze-frame data, and note any related high-circuit or continuously energised actuator codes that might confirm a short-to-voltage pattern across multiple outputs
  2. 2
    With the ignition on and the bypass "B" valve connector disconnected, measure voltage on the harness-side signal wire; reading near battery voltage when the ECM is not commanding the valve confirms a short to B+ in the harness
  3. 3
    Visually inspect the bypass "B" harness from the valve connector to the ECM, concentrating on areas near battery cables, ignition wiring, and the underbonnet fuse/relay box where a chafe to a live circuit is most likely
  4. 4
    Inspect the bypass "B" connector for bridged terminals, melted plastic indicating previous overheating, or pushed-back pins that may be contacting an adjacent live pin
  5. 5
    Check the relay and fuse for the bypass "B" supply circuit; test relay contact resistance and verify contacts open correctly when de-energised — a welded relay contact will permanently supply voltage regardless of ECM commands
  6. 6
    Measure the solenoid coil resistance with the connector disconnected; an abnormally low reading (near short circuit) confirms an internal coil short that requires actuator replacement
  7. 7
    After harness and component repairs, clear all codes, monitor bypass circuit live data under a range of engine conditions including boost, and confirm P022F does not recur before closing the repair

Related powertrain codes

Frequently asked questions

What is the risk of leaving P022F unrepaired if the car still drives?

The primary risks are two-fold. First, the bypass valve held in a fixed position degrades intercooler thermal management, which over time reduces engine efficiency and can promote knock on petrol engines. Second, if a short to voltage is holding the solenoid coil continuously energised, the coil will overheat and fail — converting a relatively inexpensive wiring repair into a more expensive actuator replacement. Prompt diagnosis prevents escalation.

Can P022F and P022E be stored at the same time?

Yes, though it is uncommon for both high and low circuit codes to be stored simultaneously on the same circuit under normal fault conditions. If both codes appear together, it may indicate an intermittent fault that has tripped both thresholds at different points, a scan tool that is reporting historical codes from separate ignition cycles, or in rare cases a circuit oscillating rapidly through its range due to a marginal connector or damaged ECM driver.

Does P022F affect the "A" circuit as well?

No, P022F specifically refers to the "B" bypass control circuit. The "A" circuit has its own discrete codes: P022B (low) and P022C (high). If both "A" and "B" circuit faults appear simultaneously, suspect a shared wiring fault in a common harness section, a shared supply that has developed a short, or broader ECM output driver issues.

Will a wiring repair require any ECM recalibration afterwards?

In most cases no. Repairing the harness short and replacing the actuator if damaged is sufficient; the ECM re-evaluates the circuit on the next key cycle and clears the fault conditions if the circuit now reads within specification. However, on some platforms with adaptive bypass control learning, clearing codes and performing a defined drive cycle or bypass valve adaptation procedure may be required to allow the ECM to relearn valve position endpoints. Consult the vehicle-specific service information.

Disabling P022F in software

RaceTune can permanently disable P022F — 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.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

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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