P0731: Gear 1 Incorrect Ratio
Can you still drive? Not recommended. First gear slippage means the transmission is not transferring power properly from a stop. This can worsen rapidly and lead to complete failure.
What Does P0731 Mean?
Code P0731 means the TCM detected an incorrect gear ratio specifically in 1st gear. The input-to-output speed ratio does not match what 1st gear should produce, indicating the 1st gear clutch pack is slipping or a speed sensor is malfunctioning. First gear handles the highest torque multiplication, so wear here is significant.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Worn 1st gear clutch pack
- Low transmission fluid pressure
- Burnt or contaminated transmission fluid
- Faulty input or output speed sensor
- Worn 1st gear band
Symptoms
- Check engine light on
- Slipping when starting from a stop
- Delayed or harsh 1-2 shift
- RPM flare when accelerating from stop
- Vehicle feels sluggish in 1st gear
Diagnostic Steps
- 1Check transmission fluid level and condition
- 2Verify input and output speed sensor readings in 1st gear
- 3Monitor gear ratio in 1st gear with scan tool during controlled acceleration
- 4Perform line pressure test
- 5Check for other gear ratio codes to determine if problem is isolated to 1st gear
- 6Inspect valve body for stuck valves if possible
Recommended Parts & Tools
transmission fluid
transmission filter kit
OBD-II scan tool with TCM access
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $250 - $4500 |
| Parts Only (DIY) | $80 - $200 |
| Labor (1-2 hrs @ $100/hr) | $100 - $200 |
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Chat with AI About P0731Commonly Affected Vehicles
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Frequently Asked Questions
Can a fluid change fix P0731?
If the fluid is low or severely degraded, a fluid and filter change may help if the clutch packs are not too far gone. However, if there is significant debris in the pan, internal damage is likely.
What does a gear ratio code mean for my transmission?
A gear ratio code means the transmission is slipping in that specific gear. The computer detects the input and output shafts are not spinning at the ratio expected for that gear, which indicates internal wear or a sensor fault.
Community Fix Reports
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