C0236
Rear Wheel Speed Circuit Range/Performance
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Code C0236 means the Electronic Brake Control Module has detected a missing or erratic signal from the rear wheel speed sensor. This sensor generates an alternating current (AC) signal as the wheel turns, and the EBCM uses the frequency of this signal to calculate wheel speed. This information is critical for ABS, traction control, stability control, and in many vehicles, the speedometer.
One of the telltale symptoms of this code is a speedometer that reads zero at low speeds (under 15-20 mph) and then suddenly jumps to the correct reading, or ABS that activates unexpectedly during light braking at low speeds. The brake pedal may pulsate even when gentle braking on dry pavement, and you may see a "Service Brake System" message.
This is a relatively common and often affordable repair. Start by inspecting the rear wheel speed sensor for damage, debris, or metallic contamination on the sensor tip. Check the wiring running from the sensor to the EBCM for chafing or corrosion, especially near the axle and suspension components where movement occurs. A new wheel speed sensor is typically $20-$60 and is a straightforward replacement on most vehicles.
Severity
Symptoms
- •ABS warning light on
- •Speedometer reads zero or is erratic at low speeds
- •ABS activates unexpectedly at low speeds
- •Traction control light illuminated
- •Brake pedal pulsates during normal low-speed stops
- •Service Brake System message on dash
Likely Causes
The rear wheel speed sensor generates an AC signal as the wheel turns. A cracked, contaminated, or worn sensor can produce a weak or missing signal that the EBCM cannot read reliably.
The rear wheel speed sensor wiring runs the entire length of the vehicle and is vulnerable to road debris, salt corrosion, and damage from suspension movement.
The tone ring on the axle or hub that the speed sensor reads can become cracked, have missing teeth, or accumulate metallic debris, creating erratic or missing signals.
A worn wheel bearing can allow the tone ring to wobble relative to the sensor, causing the air gap to vary and producing an inconsistent speed signal.
The speed sensor input circuitry within the EBCM can fail, though this is less common than external causes.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the rear wheel speed sensor
- Repair or replace damaged wiring and connectors in the speed sensor circuit
- Clean or replace the tone ring (reluctor ring)
- Replace the wheel bearing assembly if excessive play is found
- Clear codes and test drive to verify repair