moderatePro shop 1–3 hours (dealer) Community experience2,587 views
Source: Widely reported by owners. Not a GM statement. Confirm with a qualified technician. Some low-speed DCT behavior is normal.
When to stop driving
Stop driving and contact the dealer if you see a transmission warning, the car won't move, or it loses drive. Ordinary low-speed DCT clunks are usually not a safety issue but should be checked.
Symptoms
- Clunk when shifting into drive or reverse
- Shudder when pulling away slowly
- Jerky creeping in traffic
- Harsh engagement when cold
Likely causes
- Normal dual-clutch engagement characteristics
- Software calibration that may be updated
- Clutch adaptation needing to be re-learned
- Driveline or mount issues in some cases
What to check
Diagnostic steps, in order. Stop if any step needs tools or skills you don't have.
- 1Note when it happens: cold or warm, forward or reverse, on an incline or flat.
- 2Compare with another C8 if possible to judge what's normal.
- 3Ask a dealer to check your VIN for applicable software updates or service information.
- 4Have the dealer scan for codes and check clutch adaptations.
Possible solutions
- Dealer software update if applicable
- Clutch adaptation re-learn
- Driveline or mount repairs if found
Parts commonly needed
- None for software updates
- Transmission fluid (if service is due)
- Mounts or driveline parts (if found)
Warning signs
- Behavior getting worse
- Transmission warning messages
- Burning smell
Prevention
- Follow the maintenance schedule in your owner's manual
- Avoid holding the car on hills using light throttle
- Keep software up to date at the dealer
Information here combines factory data and owner experience and may not apply to your exact car. For brakes, steering, suspension, fuel or anything safety-critical, consult a qualified mechanic. Read the full disclaimer.
Community discussions
Owners who dealt with this problem
No discussions yet. Be the first to start one.
Share your experience with this problem