C0242 code meaning
PCM Indicated Traction Control Malfunction
What C0242 means
C0242 is a GM brake module code that the accessible J2012 lists do not contain. The Saab 9-5 and 9-4X of 2011 describe it as Powertrain Control Module Indicated Traction Control Malfunction, and the GM bulletin PIC4740C for the 2007 Cadillac STS calls it ECM Indicated TCS Malfunction. During traction control the brake module asks the engine module over the data bus for less torque. When the engine module holds certain faults of its own, it replies that it cannot cut torque, and the brake module stores C0242. Traction and stability control then stay off for the ignition cycle and their lamp comes on. The real fault sits in the engine or transmission module, so its codes are read first; in PIC4740C a loose transmission connector X1 was the cause.
C0242 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0242
- Traction or stability control lamp on, systems disabled
- Check engine lamp or reduced engine power from the engine side fault
Common causes of C0242
- Most likelyStored fault in the engine control module that blocks torque reduction
- PossibleLoose or poorly seated terminals at the transmission connector (GM PIC4740C)
- Less likelyFaulty engine control module, rarely the brake module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Powertrain control moduleABS control moduleCommunication bus
What each part of C0242 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 42 | The exact fault in that area. |
What to do next
- Note C0242 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0242
What does C0242 mean?
C0242 means "PCM Indicated Traction Control Malfunction". C0242 is a GM brake module code that the accessible J2012 lists do not contain. It is a generic code, so it means the same on every make.
Is it safe to drive with C0242?
Drive gently and only to a workshop. With C0242 the car can go into limp mode (reduced power) to protect itself.
Will C0242 fail an emissions test?
C0242 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0242 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C0242 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.