ABS and brakes

C0242 — ECM Indicated Traction Control (TCS/VSES) Malfunction

Severity: medium Drive with care, to a shop

What C0242 means

C0242 means the engine control module (ECM/PCM) received a fault message from the traction control and stability system, or lost proper communication with it. This system normally works with the electronic brake control module (EBCM): it uses wheel speed data to spot wheel slip and asks the ECM to cut engine torque. When that request or link fails, the system shuts down and turns on warning lights.

Symptoms

  • Traction control or stability warning light on
  • ABS warning light on
  • Traction and stability control not working
  • Poorer grip on slick roads and possibly longer stopping distances
  • Reduced engine power on some models

Possible causes

  1. Poor connection or corrosion at the EBCM connector
  2. Open, shorted, corroded or damaged wiring harness
  3. Failed EBCM
  4. Communication fault between the ECM and EBCM
  5. Fault in the TCS request circuit
  6. Engine misfires interfering with torque reduction
  7. Failed ECM (uncommon)

How to diagnose

  1. Scan all modules (engine, ABS/EBCM) and review freeze frame data
  2. Fix any other codes first, especially misfires, wheel speed sensors and CAN bus faults
  3. Inspect the EBCM connector and harness for moisture, corrosion, chafing and loose pins
  4. Check power and ground supply at the EBCM
  5. Test the communication circuit between the ECM and EBCM with a multimeter or scope
  6. Check ABS/TCS fuses and relays
  7. Compare wheel speed readings on a scan tool while driving or spinning the wheels
  8. If wiring is good, test the EBCM and ECM with factory-level equipment

Common fixes

  • Clean, re-pin or replace damaged connectors and terminals
  • Repair or replace the damaged wiring harness
  • Repair or replace the EBCM, with any needed programming
  • Replace or reflash the ECM if confirmed faulty

Questions and answers

What does code C0242 mean?

The engine computer detected a fault in the traction and stability control system or in its link to the brake module. The most common sources are the EBCM, its connector or the wiring.

Can I drive with code C0242?

Yes, carefully and only until it is repaired, since the brakes normally work. Traction control and possibly ABS are off, so drive slower on wet or slippery roads.

How do I fix C0242?

Start by checking the EBCM connector, harness, power and ground. Replace the control module only after ruling out wiring problems and other codes.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.