The C0055 code indicates that the vehicle's control module has detected a fault in the 'D' signal circuit from the steering wheel position sensor. This sensor measures the steering wheel angle and rate of turn, and the 'D' signal is typically one of several redundant or complementary outputs used for stability control and steering system functions. The code sets when the signal is missing, out of range, or does not match expected values.
The sensor itself may have internal electrical or mechanical failure, causing an incorrect or missing signal D output. This is the most common cause when no other wiring issues are present.
Chafed, broken, or corroded wires and terminals in the sensor circuit can interrupt the signal. This often occurs near the steering column or where the harness flexes.
Loose, backed-out, or oxidized pins at the sensor connector can cause intermittent or high-resistance faults on the signal D circuit.
The clock spring provides electrical connections to the steering wheel and may also carry the position sensor signal. A broken or worn clock spring can disrupt the signal.
After a wheel alignment, steering component replacement, or battery disconnect, the sensor may require recalibration. An uncalibrated sensor can send implausible signal D values.
The module that interprets the sensor signal may have an internal fault, though this is rare. It should only be considered after all other causes are ruled out.
The vehicle may be drivable, but electronic stability control and traction control systems are likely disabled, which could affect handling in emergency maneuvers. It is advisable to repair the fault promptly.
Many steering angle sensors have multiple outputs (e.g., Signal A, B, C, D) for redundancy and cross-checking. Signal D is one of these outputs, and the code indicates a problem specific to that circuit or the data it carries.
Recalibration is often required after a wheel alignment or battery disconnect, but if the sensor is faulty, recalibration will not fix the code. Proper diagnosis will determine whether the sensor itself has failed.
No, it is very rare for the control module to be the root cause. The problem is almost always the sensor, its wiring, or calibration. Replacing the module without thorough testing is likely to be an expensive misdiagnosis.