P022C

Charge Air Cooler Bypass Control A Circuit High

P022C is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Bypass Control A 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
P022C
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P022C means

P022C is the complement to P022B and is logged when the ECM detects a higher-than-expected voltage or current value in the charge air cooler bypass control "A" circuit. The charge air cooler bypass system uses an electronically controlled valve — solenoid, vacuum actuator, or motor-driven — to divert compressed intake air around or through the intercooler depending on engine operating conditions such as load, temperature, and transient demand. The ECM continuously monitors the control circuit's electrical state against calibrated high and low thresholds. A high-side fault indicates that the circuit is presenting more electrical energy than commanded: the most common cause is a short to battery voltage (B+) in the harness or connector, which forces the signal line to read as fully energised regardless of ECM commands. An internal ECM driver failure that locks the output high is another possibility. In either case the ECM can no longer modulate the bypass valve position, resulting in a fixed default state that causes thermal management of the intake charge to operate open-loop. On turbocharged applications this degrades intercooler efficiency, disrupts the fuelling model, and typically triggers a power-reduction strategy. Persistent high-circuit faults carry a risk of overheating the bypass actuator coil if it is continuously energised above its rated duty cycle.

Common causes

Most-frequently reported root causes when P022C is logged.

  • 1
    Short to battery voltage (B+) in the bypass control circuit wiring or connector, forcing the signal line permanently high
  • 2
    Bypass valve actuator coil internal short creating an abnormally high voltage feedback condition
  • 3
    Bypass valve stuck open or closed due to mechanical damage, seized pivot, or foreign object obstruction
  • 4
    Damaged wiring insulation causing a chafe contact with an adjacent live circuit or chassis ground
  • 5
    Defective fuse, relay, or inline connector with an internal short supplying excess voltage to the control circuit
  • 6
    Corroded or bridged connector pins creating an unintended electrical path to a higher voltage source
  • 7
    ECM output driver fault locking the bypass control output in a high state (rare; only after harness and actuator faults are excluded)

Symptoms drivers notice

MIL (Check Engine Light) illuminated with P022C stored, often accompanied by charge-air temperature or boost pressure related codes
Reduced engine power and sluggish throttle response as the ECM restricts output when bypass valve authority is lost
Vehicle entering limp mode or power-derate as a protective measure against uncontrolled charge-air temperature
Engine misfiring or rough running caused by the fuelling model receiving incorrect intake air temperature data
Possible bypass actuator overheating if the coil is held continuously energised beyond its rated duty cycle
Poor fuel economy across all driving conditions due to loss of intake thermal management

How to diagnose P022C

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored DTCs and freeze-frame data with a scan tool; note any companion boost, temperature, or turbocharger codes that indicate wider system impact
  2. 2
    Visually inspect the charge air cooler bypass valve, actuator, and the wiring harness routing for heat damage, chafing against sharp edges or hot components, and any sign of insulation melting
  3. 3
    Disconnect the bypass valve connector and measure voltage on the circuit wire at the harness side with the ignition on; a reading near battery voltage when the ECM is not commanding the valve indicates a short to B+ in the harness
  4. 4
    Inspect the connector for bridged, corroded, or pushed-back pins that could create an unintended high-side connection; clean or replace the connector as required
  5. 5
    With the valve connector disconnected, use a DVOM to perform a wiring continuity and insulation resistance check from the ECM pin to the valve connector, verifying no short to voltage exists along the harness
  6. 6
    Use a scan tool actuator test to command the bypass valve while monitoring commanded state versus live data feedback; compare actual current draw to specification to confirm whether the fault is in the wiring or the ECM driver
  7. 7
    If all external wiring and mechanical checks pass, test the ECM control output with a manufacturer-level diagnostic tool before suspecting module failure

Related powertrain codes

Frequently asked questions

What distinguishes P022C from P022B?

P022B (Circuit Low) points to a signal below the expected threshold — typically an open circuit, high resistance, or weak actuator. P022C (Circuit High) means the signal is above the expected range, which usually indicates a short to voltage in the harness or an ECM driver stuck in the on state. The diagnostic approach differs: P022C requires checking for unwanted voltage sources, while P022B focuses on continuity and resistance.

Can a short to voltage in the bypass control circuit damage the ECM?

Yes, sustained short-to-voltage conditions can overstress the ECM's output driver. Modern ECMs have protection circuits that can shut down the driver to prevent internal damage, but a prolonged or high-current fault can still cause permanent driver failure. Address the harness short before reconnecting or replacing the ECM.

Is it safe to clear P022C and continue driving?

Clearing the code without repairing the fault is not recommended. The underlying short to voltage may continue to stress the actuator and ECM driver. The code will return immediately if the fault persists. The vehicle may also remain in limp mode regardless of clearing the code if the ECM detects the fault condition on restart.

Which vehicles commonly set P022C?

P022C is a generic SAE code applicable to any turbocharged or supercharged vehicle with an electronically controlled charge air cooler bypass valve. It is most commonly seen on European turbocharged diesels and direct-injection petrol engines (Ford EcoBoost, VAG TSI/TDI, BMW N- and B-series, Renault dCi), but can appear on any forced-induction platform that uses this bypass architecture.

Disabling P022C in software

RaceTune can permanently disable P022C — 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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