P022D
Charge Air Cooler Bypass Control B Circuit OpenP022D is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Bypass Control B 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.
What P022D means
P022D is stored when the ECM detects a general fault or open-circuit condition in the charge air cooler bypass control "B" circuit. On vehicles equipped with a two-bank or dual-stage intercooler system, the "B" designator refers to the second bypass control circuit, typically serving the second intercooler bank, a secondary bypass solenoid, or an alternative airflow path for a different cylinder bank. An open circuit occurs when the electrical path between the ECM and the bypass actuator is broken — most commonly caused by a severed wire, a disconnected connector, a failed actuator coil that has gone open-internally, or a blown circuit protection device. When the ECM commands the "B" bypass valve and detects no current flow or feedback confirming movement, it logs P022D and may disable turbocharger boost enhancement on the affected circuit as a protection strategy. Unlike the low/high circuit variants, the open designation is more definitive: the circuit has no measurable continuity. This makes initial diagnosis somewhat more straightforward — a DVOM continuity check will directly confirm the break — but finding the break point along a routed harness can still be time-consuming. On single-intercooler vehicles that nonetheless carry a "B" circuit code, the "B" designation may simply refer to a second solenoid controlling a different aspect of the same bypass valve assembly.
Common causes
Most-frequently reported root causes when P022D is logged.
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1
Broken or severed wire in the charge air cooler bypass "B" circuit harness, creating a complete open in the control path
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2
Disconnected or partially engaged connector at the bypass valve or along the harness routing to the ECM
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3
Bypass actuator coil open internally — the coil winding has failed, presenting infinite resistance to the ECM driver
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4
Blown fuse or failed relay in the supply circuit for the "B" bypass control, cutting power to the actuator
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5
Corroded or fractured connector terminal that has lost mechanical contact with the mating pin
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6
Harness damage from heat, vibration, or chafing against turbo or exhaust components causing wire breakage
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7
ECM internal open on the "B" bypass driver output (rare; diagnose only after all external circuit faults are eliminated)
Symptoms drivers notice
How to diagnose P022D
A typical diagnostic flow when this code is present.
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1
Use a scan tool to read all active and pending codes alongside freeze-frame data; an open circuit code with no related high- or low-circuit codes typically confirms a genuine break rather than a signal swing
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2
Inspect the entire bypass "B" circuit harness visually from the ECM connector to the bypass valve, focusing on areas near turbocharger heat sources, sharp metal edges, and high-vibration mounting points where wire breaks commonly occur
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3
Disconnect the bypass valve connector and test actuator coil resistance with a DVOM; infinite resistance (OL) confirms an open coil that requires actuator replacement
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4
With the connector disconnected, perform a continuity test from the ECM pin to the valve harness connector terminal; no continuity confirms a wire break that must be traced and repaired
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5
Inspect all fuses and relays associated with the bypass control circuit; replace any blown fuse but investigate the cause of the fuse failure before reinstalling to avoid a repeat fault
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6
Check the connector at both the bypass valve and the ECM for corroded, pushed-back, or fractured terminals; reseat or replace the connector and retest
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7
After repairs, clear codes, perform a test drive under boost conditions, and confirm P022D does not return before closing the repair
Related powertrain codes
- P0065 — Air Assisted Injector Control Range/Performance
- P0066 — Air Assisted Injector Control Circuit or Circuit Low
- P0067 — Air Assisted Injector Control Circuit High
- P0087 — Fuel Rail/System Pressure - Too Low
- P0088 — Fuel Rail/System Pressure - Too High
- P0089 — Fuel Pressure Regulator 1 Performance
Frequently asked questions
What does the "B" circuit designation mean in P022D?
The SAE J2012 naming convention uses letter suffixes (A, B, C…) to distinguish between multiple instances of the same component type. For charge air cooler bypass, "A" typically refers to the primary bypass valve or the first bank on a dual-intercooler system, and "B" refers to the secondary valve or second bank. Some single-intercooler vehicles use "B" to reference a second solenoid on the same bypass assembly. Always check the vehicle-specific wiring diagram to confirm which physical circuit maps to the "B" designation.
How is an open circuit different from a low circuit (P022E)?
An open circuit (P022D) means the electrical path is completely broken — no current can flow at all. A low circuit (P022E) means current can flow but the signal is below the expected threshold, which may indicate high resistance, a partial break, or a weak actuator rather than a complete break. A DVOM continuity check will read infinite resistance for an open, but will show some resistance (often higher than spec) for a low-circuit fault.
Can P022D be caused by a software or calibration issue?
Rarely. P022D is a hardware circuit fault by definition — the ECM cannot detect an open circuit unless the physical circuit is broken. However, a software bug that incorrectly interprets feedback thresholds could theoretically log P022D without a true open. Check for manufacturer technical service bulletins (TSBs) and ensure the ECM firmware is up to date before replacing parts, especially if the code appears immediately after a battery disconnect or reflash.
Will the vehicle pass an emissions test with P022D active?
No. Any active stored DTC that illuminates the MIL will cause a failure on OBD-II emissions readiness checks in most jurisdictions. Even if the charge air cooler bypass system does not directly affect tailpipe emissions during the test cycle, the active fault light alone is a fail condition. The code must be repaired and the MIL extinguished before presenting for an emissions inspection.
Disabling P022D in software
RaceTune can permanently disable P022D — 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.
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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