P0730
Incorrect Gear Ratio
High· Fix promptlyProfessionalPowertrainGeneric, all makes
What it means
The transmission computer compares input and output shaft speeds and has found a ratio that does not match any gear. The transmission is slipping.
Is it safe to drive?
Drive gently and only as far as needed. A slipping transmission can fail completely.
Symptoms
- Slipping
- Harsh or delayed shifts
- Limp mode
Probable causes
Most likely first
- 1Low or degraded fluid
- 2Worn clutches or bands
- 3Faulty solenoids or valve body
- 4Faulty speed sensor
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Check the transmission fluid level and condition first (follow the maker's procedure; many need the engine running and the fluid hot). Dark, burnt-smelling fluid or metal debris points to internal wear.
- 3Check which gear-specific codes are also stored.
- 4Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Fluid service
- Valve body or solenoid repair
- Transmission rebuild
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.