P0731 — Gear I Incorrect ratio
Category: Powertrain Severity: High
Updated:
DTC code P0731 means: Gear I Incorrect ratio. It falls under the "Powertrain" category, with an estimated severity of High. Common causes include low or degraded transmission fluid, faulty speed sensor or solenoid for the affected gear/shaft and wiring/connector issue; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Low or degraded transmission fluid
- Faulty speed sensor or solenoid for the affected gear/shaft
- Wiring/connector issue
- Internal transmission wear (worn clutch pack or band)
Symptoms
- Harsh, delayed or slipping shifts
- Transmission may enter limp/failsafe mode (stuck in one gear)
- Check engine light on
- Unusual noise when shifting
How to diagnose it step by step
- Check the ATF.
- Check 1st gear ratio.
- Check solenoids.
- Evaluate repair.
How to fix it
Start by checking the transmission fluid level and condition — many of these codes trace back to low or old fluid. If the fluid is fine, the affected sensor or solenoid is the next suspect; internal mechanical wear is the last, more expensive possibility and usually needs a specialist.
Estimated repair cost
$200–4,500.
Frequently asked questions
What does DTC code P0731 mean?
Gear I Incorrect ratio.
Is code P0731 serious?
Severity High. Have it checked as soon as possible, especially if it affects safety or the catalytic converter.
Can I keep driving with code P0731?
Not recommended.
Related codes
P0730 P0732 P0733 P0734 P0735 P0740 P0741 P0720 P0743 P0744
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