Code Definition

C1991 (60) — Module Calibration Failure

System: Chassis  |  Type: Manufacturer-Specific  |  Make: Ford

About C1991

C1991 is a manufacturer-specific chassis diagnostic trouble code recorded for Ford vehicles. It belongs to the C-prefix family of codes, which covers chassis, braking, steering, suspension, or stability-control faults.

Scanning & clearing: Chassis (C) codes are stored in the ABS, traction control, or stability-control modules. An enhanced or OEM-level scan tool is usually required to read and clear them.

C1991 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The control module associated with this DTC, commonly the Body Control Module (BCM), Image Processing Module (IPMA), or another feature-specific module, performs self-checks to verify that required calibration data is present, valid, and within expected parameters. DTC C1991 with subcode :60 is set when the module detects that calibration data is missing, corrupted, incompatible, or has not been successfully completed following programming, module replacement, or a battery voltage interruption. As a result, the affected system function is disabled to prevent incorrect operation.

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