P0730 — Incorrect gear ratio
Incorrect gear ratio. Common causes: Worn clutches|Fluid level low|Solenoid stuck|Failed shift.
Look up listed providers near you and give them this code when you call.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Worn clutches
- Fluid level low
- Solenoid stuck
- Failed shift
- Rebuilding transmission before checking fluid
First moves (roadside)
- Check fluid level and condition
- Solenoid resistance check
FAQ
Incorrect gear ratio. Common causes: Worn clutches|Fluid level low|Solenoid stuck|Failed shift.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Worn clutches. Other possibilities include Fluid level low; Solenoid stuck; Failed shift; Rebuilding transmission before checking fluid.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
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.