Powertrain
generic / SAE
P0731
Gear 1 Incorrect Ratio
When gear 1 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 1 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 1.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number7 / 31
Possible causes
- 1st gear clutch pack worn high
- Line pressure low (pump or valve body) medium
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
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 500–4000 €
- Estimated time: 4–16 h
- Component: transmission clutch pack
- Component: transmission valve body
- Component: transmission fluid
- MIL / check engine light
- limp mode possible
Sources
References
sae:J2012