C0242
PCM Indicated Traction Control Malfunction
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Code C0242 means the Electronic Brake Control Module (EBCM) has received a message from the Powertrain Control Module (PCM/ECM) indicating that the engine computer cannot perform the torque reduction needed for traction control. Traction control works by both applying brakes to spinning wheels and reducing engine power — when the PCM cannot do its part, the EBCM stores this code.
This code is often a secondary fault. The root cause is frequently a powertrain issue that has caused the PCM to set its own diagnostic trouble codes, which in turn prevents it from participating in traction control. Common triggers include misfire codes, throttle body faults, or transmission-related DTCs. Always check for and repair any engine or transmission codes before addressing C0242.
Start diagnosis by scanning both the ABS and powertrain modules for stored codes. If there are engine codes present, repair those first and then clear all codes. In many cases, C0242 will not return once the underlying powertrain issue is resolved. If no powertrain codes are found, the problem may be in the serial data communication between the two modules or an internal EBCM fault.
Severity
Symptoms
- •Traction control warning light illuminated
- •ABS light may be on
- •Service StabiliTrak or stability system message
- •Traction control does not engage when wheels spin
- •Check engine light may also be on
- •Reduced engine power in some conditions
Likely Causes
When certain powertrain DTCs are set in the PCM/ECM, the engine control module disables its ability to reduce torque for traction control and communicates this to the EBCM via serial data.
Serial data communication issues between the Powertrain Control Module and the EBCM can cause invalid or missing traction control messages, triggering this code.
An erratic wheel speed sensor signal can cause the traction control system to receive conflicting data, leading the PCM to report a malfunction to the EBCM.
The EBCM may incorrectly interpret valid serial data from the PCM as a malfunction due to an internal processing fault.
Physical damage to the Controller Area Network wiring between modules can corrupt the traction control messages exchanged between the PCM and EBCM.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Diagnose and repair any powertrain DTCs stored in the PCM first
- Inspect and repair CAN bus wiring between PCM and EBCM
- Replace faulty wheel speed sensor if signal is erratic
- Replace EBCM if internal processing fault is confirmed
- Clear codes and test drive to verify traction control operation