C0321

Transfer Case Lock Circuit

C0321 is a generic OBD-II chassis diagnostic trouble code: Transfer Case Lock Circuit. It is logged by the engine control unit when the chassis monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code

C0321

Group

Chassis

System

Chassis

Severity

—

Need C0321 disabled?

RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.

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Detailed reference content for C0321 is being prepared. What you see above — the code's group, system, and the software disable option below — is accurate and complete; the long-form explainer, common causes, symptoms, and diagnostic steps will appear here once they have been reviewed.

Related chassis codes

Disabling C0321 in software

RaceTune can permanently disable C0321 — 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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