C1234 - FAULT CODE - OBD2

C1234 Code failures by brands

C1234 BUICK, CADILLAC, CHEVROLET, GMC, PONTIAC: LEFT REAR WHEEL SPEED CIRCUIT OPEN OR SHORTED

Description of DTC code C1234

Wheel Speed Sensors are devices that feature a reluctance ring or wheel. When the ring has movements, the teeth of the ring create interruptions to a magnetic field, an action that produces electrical pulses that are provided to a controller (EBCM), which interprets them as the speed of the wheel.

C1234 OBD2 diagnostic code is stored when the Left Rear Wheel Speed Sensor has erratic operation caused by an open or shorted circuit.

Symptoms of fault code C1234

Check Engine light on.
ABS warning light on.

Causes of OBD2 C1234

The reasons for the C1234 OBDII fault code are as follows:

Left Rear Wheel Speed Sensor wiring may have been damaged.
The Left Rear Wheel Speed Sensor circuit may have poor connections.
The Left Rear Wheel Speed Sensor may be faulty.
The hub assembly (of which this speed sensor is also a part) could be in poor condition.

Possible solutions of the DTC code C1234

In order to resolve the DTC C1234 OBD2 code you must do the following:

To start the diagnosis consult the TSB.
Inspect the wiring of the Left Rear Wheel Speed Sensor circuit for corrosion or burnt wiring deficiencies. If one of these damages is discovered, proceed with the necessary repairs.
Perform electrical tests on the Left Rear Wheel Speed Sensor circuit. Note that the code indicates that the circuit is open or shorted, so locate the condition and repair it.
Following the manufacturer's diagnostic steps, check the Left Rear Wheel Speed Sensor for proper condition. If after performing these tests you determine that the sensor is damaged, consider replacing it.