C0237: Rear Wheel Speed Signal Erratic

What it means

This code has no generic meaning assigned by SAE J2012 or ISO 15031-6. Any description for it is manufacturer-specific.

How it works

C0237 is not a standardized OBD-II definition, so the title alone cannot identify which rear wheel or signal the vehicle monitors. If the vehicle-specific definition matches this title, the brake control module is checking a rear wheel-speed signal and sets the code when it behaves erratically; confirm the exact wheel and test conditions in vehicle-specific service information.

Common causes

Most likely first.

1. Manufacturer-specific diagnostic definition
2. Vehicle-specific scan-tool decoding

Symptoms

• Symptoms depend on the vehicle-specific meaning

How to diagnose it

1. Read the code with a scan tool that can access the brake control module and confirm the vehicle-specific description before selecting a wheel or circuit to test.
2. Check freeze-frame or event data, if available, for vehicle speed and the rear wheel-speed readings when the fault occurred.
3. Inspect the identified rear sensor, connector, wiring, and tone ring or encoder for looseness, contamination, damage, or chafing.
4. Compare live wheel-speed readings while turning the wheels or during a cautious low-speed check, following the manufacturer's test procedure.
5. If the signal drops or jumps, test the identified sensor circuit and sensor using the vehicle-specific wiring diagram and manufacturer's specification.

Common fixes

• Clean and secure the identified rear sensor connector.
• Repair chafed or damaged wiring to the affected rear sensor.
• Clean or replace a damaged tone ring or encoder.
• Replace the rear wheel-speed sensor if testing confirms it is faulty.

Can I keep driving?

Until the exact vehicle-specific fault is confirmed, assume ABS or stability control may be limited and drive cautiously, leaving extra stopping distance. If the brake warning light is on or braking feels abnormal, stop safely and arrange inspection.