P1721
Gear 1 Incorrect Ratio
P1721 is an OBD-II diagnostic trouble code meaning: Gear 1 Incorrect Ratio. Common causes: low or contaminated transmission fluid, worn friction discs or clutches. Estimated repair cost: $56–278.
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
Related codes
Error P1721 by Vehicle Brand
FAQ
What does the P1721 code mean?
P1721 is an OBD-II diagnostic trouble code that indicates: Gear 1 Incorrect Ratio
What causes a P1721 error code?
The most common causes of P1721 include: Low or contaminated transmission fluid; Worn friction discs or clutches; Input shaft speed sensor malfunction; Output shaft speed sensor malfunction.
How do I fix a P1721 diagnostic trouble code?
To fix P1721: 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. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P1721?
Limited driving only, diagnose soon
How much does it cost to fix P1721?
The estimated repair cost for P1721 is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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