Fault code C1237 – a step-by-step guide to diagnosing and fixing it

Error code C1237 is displayed and the check engine light is on - what does this mean?

DTC C1237 is recognized by the OBD/EOBD system and indicates a problem with the right rear wheel speed sensor. This error code occurs when the ABS control unit receives an implausible or missing signal from the sensor. This trouble code may have slightly different names for different manufacturers, but basically refers to the same component.

What causes can this error code have?

• Defective right rear wheel speed sensor
• Damaged or interrupted sensor cable
• Corroded or loose plug connections
• Dirty or damaged sensor ring (pulse ring)
• Defective ABS control unit
• Excessive air gap between sensor and pulse ring
• Mechanical damage to the wheel bearing
• Short circuit in the sensor wiring

What symptoms occur in parallel with fault code C1237?

• ABS indicator light: The ABS warning light in the dashboard lights up continuously
• ESP malfunction: The electronic stability program is not working properly
• Braking problems: Extended braking distances or locking wheels under heavy braking
• Speedometer inaccuracies: Fluctuating or incorrect speed display
• Cruise control failure: The cruise control no longer works
• Jerking when braking: Uneven braking power at the wheels

How to fix the problem of error code C1237?

• Repairing fault code C1237 requires a systematic approach to identify the exact cause.
• Sensor replacement: Replace the defective right rear wheel speed sensor completely and set the correct air gap to the pulse ring in the process
• Cable repair: Locate damaged wiring, replace defective sections and properly insulate all connections
• Clean plug connections: Thoroughly clean and decorrode all sensor plug contacts and treat with contact spray
• Pulse ring maintenance: Clean the sensor ring on the wheel bearing or replace it completely if damaged
• Control unit reset: After repair, delete the fault memory and have the ABS system recalibrated
• Complete wheel bearing replacement: In the event of mechanical damage, replace the entire wheel bearing including the integrated sensor