OBD-II trouble code
C0240: Powertrain Control Module (PCM) Traction Control Not Allowed
The brake/stability module disabled traction control because the engine computer reported it can no longer manage engine torque. This is a secondary flag — the real problem is a separate engine or sensor fault that must be found first.
Quick facts
- System
- Chassis
- Category
- ABS / Traction Control
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $75 – $700
- DIY difficulty
- Intermediate DIY
What does C0240 mean?
C0240 is a chassis code that means the Electronic Brake Control Module (EBCM) has disabled the traction control system because the Powertrain Control Module (PCM/ECM) told it, over the serial data network, that engine torque control is 'not allowed' — in other words, the engine computer has a fault that prevents it from safely reducing or managing torque on command. Traction control works by having the brake module ask the engine module to cut torque when a wheel slips; if the engine side cannot honor that request, the whole feature is stood down.
The key thing to understand is that C0240 is a symptom, not a root cause. The EBCM is doing exactly what it should — refusing to run a safety feature that depends on a subsystem it can no longer trust. The actual fault lives in the powertrain, and it will almost always be accompanied by one or more powertrain (P) codes that tell you what went wrong. Replacing the EBCM or ABS module for a C0240 is a classic and expensive mistake.
Common triggers are engine or throttle problems that make torque control unreliable: throttle/pedal position sensor correlation faults (such as P2135 or P2138), a reference-voltage fault feeding several sensors (such as P0641), reduced-engine-power/limp conditions, an internal PCM problem, or even engine overheating. On many GM vehicles a C0240 paired with a 'Reduced Engine Power' message and P2135 points to an electronic throttle body.
Because C-code definitions vary by manufacturer, confirm your specific make and model's meaning. The diagnostic rule, however, is universal: read all stored codes and fix the underlying powertrain fault, and the C0240 will clear with it.
Common causes
- Throttle or accelerator pedal position sensor correlation fault (e.g. P2135, P2138) — the most common trigger on GM vehicles
- Sensor reference voltage circuit fault (e.g. P0641) starving multiple sensors of power
- Electronic throttle body or throttle actuator control problem, often with a 'Reduced Engine Power' message
- Reduced-power / limp mode from another powertrain fault
- Engine overheating or loss of ignition timing control by the PCM
- Internal PCM/ECM fault or a serial data problem between the PCM and EBCM
Symptoms
- Traction control and stability control (StabiliTrak/ESC) warning lights on and systems disabled
- Service Traction Control / Service StabiliTrak message
- Often a Reduced Engine Power message and sluggish acceleration
- Check engine light with accompanying powertrain codes
- In severe cases, limited or unsafe acceleration
Diagnostic steps
- 1.Scan every module and record all codes — C0240 is a secondary flag, so the accompanying powertrain (P) codes are the real story.
- 2.Diagnose and repair the underlying powertrain fault first (for example a P2135/P2138 throttle correlation or a P0641 reference-voltage fault).
- 3.If a Reduced Engine Power message is present with P2135, inspect and test the electronic throttle body and pedal assembly per the manufacturer procedure.
- 4.Verify the PCM has good power, grounds, and system voltage before suspecting the module itself.
- 5.Do NOT replace the EBCM/ABS module for C0240 — confirm the engine-side cause is fixed, then clear codes and retest.
- 6.Recheck that traction and stability control re-enable after the root powertrain code is resolved.
Repair cost
$75 – $700
Cost depends entirely on the underlying powertrain fault. Diagnosis is often $75-$150. A throttle/pedal sensor or reference-voltage repair runs $150-$400, while an electronic throttle body replacement (a very common GM fix) commonly runs $250-$700 in parts and labor. C0240 itself needs no separate repair once the root cause is fixed.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with check engine light diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.