P0731
Gear 1 Incorrect Ratio
Severetransmission
Overview
The P0731 diagnostic trouble code signals a gear 1 incorrect ratio condition detected by the transmission control module. This code relates to the automatic transmission system and may affect shift quality, timing, or overall transmission performance. Prompt attention is important to prevent further transmission damage.
Symptoms
- Loss of one or more gears
- Check Engine Light (MIL) illuminated
- Transmission overheating warning
- Shuddering or vibration during acceleration
Common Causes
- Worn or damaged internal transmission components
- Failed torque converter
- Wiring issues in the transmission harness
- Faulty input or output speed sensor
Diagnosis Steps
- 1Connect an OBD-II scanner and read all stored trouble codes and freeze frame data
- 2Check transmission fluid level and condition; top off or replace if needed
- 3Test the transmission speed sensors with a multimeter or scan tool
- 4Inspect wiring and connectors for the transmission harness
- 5Perform a transmission pressure test if accessible
Estimated Repair Cost
$300 — $2,500
Cost varies by vehicle, location, and repair shop. Includes parts and labor.
Commonly Affected Vehicles
Jeep Grand CherokeeFord ExplorerChevrolet SilveradoHyundai Santa Fe
Related Codes
More Transmission Codes
P0218Transmission Over Temperature Condition
CriticalP0700Transmission Control System (MIL Request)
SevereP0701Transmission Control System Range/Performance
SevereP0702Transmission Control System Electrical
SevereP0703Torque Converter/Brake Switch "B" Circuit
ModerateP0704Clutch Switch Input Circuit Malfunction
ModerateFrequently Asked Questions
Driving with a transmission code is risky. Continued driving can cause further damage to the transmission, resulting in significantly higher repair costs. Have it inspected as soon as possible.