P1721
Gear 1 Incorrect Ratio
Severity
⚠️ MediumCan you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–278 (est.)
Symptoms
- Incorrect gear shifting
- Delays when switching to first gear
- Slipping when starting
- Deterioration in acceleration dynamics
- Check Engine light comes on
Causes
- Low or contaminated transmission fluid
- Worn friction discs or clutches
- Input shaft speed sensor malfunction
- Output shaft speed sensor malfunction
- Problems with the hydraulic control unit
How to Fix
- Check the level and condition of the transmission fluid
- Conduct diagnostics of the input and output shaft speed sensors
- Check the condition of friction discs and clutches
- Diagnose the hydraulic control unit
- If necessary, replace worn transmission components