P0730
Incorrect Gear Ratio
The ratio between input and output speed does not match any expected gear. Indicates slippage, valve body fault or sensor inaccuracy without identifying a specific gear.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Internal slippageCommon
- Valve body faultPossible
- Speed sensor reading inaccurateLess likely
Parts involved
- Automatic Transmission
- Valve Body
- Speed Sensor
P0730 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.