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P0734 — 4th gear ratio incorrect
SerioustransmissionPower derate likely — plan to stop soon
4th gear ratio incorrect. Common causes: 4th range clutch|Solenoid.
Don't risk it — get a diesel tech on the truck.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- 4th range clutch
- Solenoid
First moves (roadside)
- Solenoid and fluid check
FAQ
What does P0734 mean?
4th gear ratio incorrect. Common causes: 4th range clutch|Solenoid.
How serious is P0734?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of P0734?
The most common cause is: 4th range clutch. Other possibilities include Solenoid.
Can I keep driving with P0734?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
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.