Code Definition

C1766 — Air Suspension Rear Height Sensor Low Signal Circuit Open

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

About C1766

C1766 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.

When C1766 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; a signal or supply voltage lower than the expected operating range; 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.

C1766 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 C1766 is a Ford specific chassis code covering the rear height sensor circuit in the four wheel air suspension system used on the Expedition, Lincoln Navigator, and related models. The rear height sensor is a potentiometer style sensor mounted between the rear axle and the frame whose voltage signal tells the air suspension control module the exact rear ride height. C1766 sets when the module detects an open circuit in the rear height sensor low signal circuit, meaning the expected electrical path is broken and no valid height reading is being returned. When the code sets the module disabl...

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