Code C0037 indicates a malfunction in the left rear wheel speed sensor circuit. The Anti-lock Brake System (ABS) module monitors this sensor to determine wheel speed, and this code triggers when the signal is missing, erratic, or out of the expected range. It directly affects ABS, traction control, and stability control operation.
The sensor itself has suffered an internal electrical failure, such as an open or shorted coil, rendering it unable to generate a signal.
Exposure to road debris and moisture causes the sensor wiring or connector to chafe, corrode, or break, interrupting the signal to the ABS module.
Corrosion on the wheel hub pushes the sensor away from the tone ring, creating an air gap that weakens the magnetic field and drops the signal.
The toothed ring the sensor reads can crack, break teeth, or accumulate debris, causing an erratic or incomplete signal.
Though rare, an internal failure in the ABS module can prevent it from reading the sensor circuit correctly.
You can drive it with caution, as standard braking will still function. However, ABS, traction control, and stability control will be disabled, meaning the wheels could lock up or slip in poor driving conditions.
Usually not. Code C0037 is a chassis code that will typically trigger the ABS and traction control warning lights. The main check engine light will only illuminate if the failure affects powertrain data, such as vehicle speed calculations on some models.
Almost never. Drivers are sometimes told to replace the Powertrain Control Module (PCM) or Engine Control Module (ECM) for wheel speed codes, but this is usually incorrect. C0037 is a chassis circuit code, and the failure is almost always the sensor, the wiring, or a mechanical issue at the wheel hub. Replacing the PCM will not fix this code.
Remove the sensor and use a wire brush or sandpaper to clean the hub mounting surface until it is smooth and flat. This restores the correct air gap between the sensor and the tone ring, allowing the magnetic signal to read properly.