Code Definition

C1166 — Speed Wheel Sensor RR Input Open Circuit

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

About C1166

C1166 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 C1166 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and 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.

C1166 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

This code relates to the stop lamp switch (brake light switch) circuit as monitored by the chassis control module, typically the ABS or stability control unit. The stop lamp switch closes when the brake pedal is pressed, supplying a brake applied signal that the module uses for functions such as ABS, traction control, brake assist, and cruise control cancellation. DTC C1166 sets when the module detects an electrical failure in the stop lamp switch circuit, such as an open circuit, a short to ground, a short to voltage, or a brake signal that disagrees with other inputs like the brake pressure ...

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