P0734
Gear 4 Incorrect Ratio
When gear 4 is engaged, the measured ratio between the input- and output-shaft speed sensors does not match the expected ratio for that gear. This means the transmission is slipping in gear 4 rather than transmitting power solidly. Causes: worn clutch packs or bands, low fluid level or pressure, a stuck shift solenoid, or a valve-body fault affecting gear 4.
- 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.
- 4th gear clutch pack wornCommon
Parts involved
- Transmission Clutch Pack
- Torque Converter
P0734 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.