P022A

Charge Air Cooler Bypass Control A Circuit Open

P022A is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Bypass Control A Circuit Open. 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
P022A
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P022A means

Diagnostic trouble code P022A is a generic OBD-II powertrain code set when the engine control module (ECM) detects an open electrical condition within the charge air cooler (CAC) bypass control circuit designated as circuit "A." The charge air cooler bypass valve is an actuated component used in turbocharged and supercharged engines to route compressed intake air around the intercooler under specific conditions — for example, during cold starts to allow faster catalyst light-off or warm-up, or to enable rapid pressure venting during compressor surge events. The ECM commands the bypass valve via a dedicated control circuit; when it measures a response that falls outside the expected electrical parameters — particularly an open-circuit condition indicating no current flow — it sets P022A and typically disables active bypass valve control, defaulting to a fixed valve position. This can impair charge air temperature regulation, turbo response, and in some calibrations triggers limp mode to protect downstream components. The code applies to any OBD-II vehicle with a charge air cooler and an electronically actuated bypass valve, including turbodiesel and turbocharged gasoline applications across many manufacturers.

Common causes

Most-frequently reported root causes when P022A is logged.

  • 1
    Open circuit in the bypass valve actuator wiring harness (broken wire, damaged insulation, or connector separation)
  • 2
    Corroded, bent, or backed-out terminal pins in the charge air cooler bypass valve connector
  • 3
    Failed bypass valve actuator (internal open in the solenoid coil or motor winding)
  • 4
    Blown fuse or failed relay in the bypass valve control circuit
  • 5
    Short to ground or open in the ECM output driver circuit for the bypass valve
  • 6
    Faulty ECM (rare; only after all wiring and actuator checks have been exhausted)
  • 7
    Air leak in the intake tract near bypass valve mounting disturbing pressure-based feedback used to infer valve position

Symptoms drivers notice

MIL illuminated with P022A stored
Reduced engine performance or hesitation on acceleration due to uncontrolled bypass valve position
Engine entering limp mode on vehicles where the ECM derates torque when boost control is compromised
Increased fuel consumption from suboptimal charge air temperature management
Turbo lag or inconsistent boost build-up, particularly noticeable during cold-start conditions
Possible increased intake noise or compressor surge if the bypass valve is stuck in the wrong position

How to diagnose P022A

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored DTCs with a scan tool; note any accompanying boost, throttle-body, or MAF codes that could indicate a broader intake system issue
  2. 2
    Visually inspect the charge air cooler bypass valve wiring harness, connector, and actuator body for physical damage, heat soak, chafing against turbo or charge pipes, and corroded terminals
  3. 3
    Check the relevant fuse and relay in the underhood or interior fuse box per the vehicle-specific wiring diagram; replace any open fuse and investigate the cause of the overload
  4. 4
    Disconnect the bypass valve connector and measure actuator resistance (solenoid coil) with a digital multimeter; an open reading (OL) confirms actuator failure; compare resistance to manufacturer specification
  5. 5
    With the connector disconnected, back-probe the ECM-side of the control circuit and measure voltage when the ECM commands the valve; absence of voltage with a known-good fuse points to an ECM driver or wiring fault between ECM and connector
  6. 6
    Perform a continuity test along the entire wiring harness from the bypass valve connector to the ECM pin, identifying any open section for repair or harness replacement
  7. 7
    After repairs, use the scan tool's actuation or output test function to command the bypass valve through its full range and confirm correct electrical response before clearing the code

Related powertrain codes

Frequently asked questions

What is the charge air cooler bypass valve and why does it exist?

The bypass valve allows boosted intake air to bypass the intercooler and flow directly into the intake manifold. This is used during cold starts to get heat into the system faster, and in some architectures to dump boost pressure rapidly during throttle lift-off, preventing compressor surge.

Can I drive with P022A active?

Short distances are generally possible, but the bypass valve being stuck in an uncontrolled position can impair charge air temperature regulation and turbo management. On vehicles that enter limp mode, drivability will be severely affected and the underlying fault should be diagnosed promptly.

Is P022A the same as a turbocharger fault?

No. P022A is an electrical open-circuit fault in the bypass valve control circuit specifically. It does not indicate a mechanical turbocharger failure, though it can affect how boost pressure builds and is managed, potentially causing secondary turbo stress if left unresolved.

Why does P022A sometimes appear after an intake system repair?

Reconnecting intake hoses, charge pipes, or intercooler ducting can inadvertently dislodge or stress the bypass valve wiring harness or connector. After any intake system work, it is good practice to visually confirm the bypass valve connector is fully seated and locked before clearing codes.

Disabling P022A in software

RaceTune can permanently disable P022A — 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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