P0742 — TCC stuck on
What it means: TCC stuck on.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Solenoid and valve body
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Louisville, KY
Closest first. Tell them P0742 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Louisville, KY · (502) 773-1159
- 0.0 mi away — based in Louisville, KY · (502) 447-1234
- 0.0 mi away — based in Louisville, KY · (502) 648-6725
What P0742 means
TCC stuck on. Common causes: Failed TCC|Stuck solenoid|Valve body.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Failed TCC
- Stuck solenoid
- Valve body
First moves (roadside)
- Solenoid and valve body
FAQ
TCC stuck on. Common causes: Failed TCC|Stuck solenoid|Valve body.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Failed TCC. Other possibilities include Stuck solenoid; Valve body.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside P0742, or share the same subsystem.
- Main shaft speed erratic (SPN 160 FMI 2)
- Input shaft speed erratic (SPN 161 FMI 2)
- Transmission output retarder speed erratic (SPN 162 FMI 2)
- Trans oil temperature very high (SPN 177 FMI 0)
- Trans oil temperature voltage high (SPN 177 FMI 3)
- Trans oil temperature voltage low (SPN 177 FMI 4)
- Engine speed signal abnormal update rate (SPN 190 FMI 9)
- Transmission output shaft speed erratic (SPN 191 FMI 2)
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.