Code Definition

C1091 — Speed Wheel Sensor All Coherency Failure

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

About C1091

C1091 is a manufacturer-specific chassis diagnostic trouble code. It belongs to the C-prefix family of codes, which covers chassis, braking, steering, suspension, or stability-control faults.

When C1091 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

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.

C1091 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

DTC C1091 is a chassis code set by the ABS, traction control, or stability control module when it detects a coherency (plausibility) failure involving all of the wheel speed sensor signals at once. The module continuously compares the four wheel speed signals against each other and against expected vehicle dynamics. C1091 sets when the relationship between the sensor signals is implausible across the whole system, rather than a single sensor simply reading out of range. Wheel speed sensors are typically hall effect (active) or magnetic reluctance (passive) devices that produce a signal proport...

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