P0731 on Jeep
Gear 1 Incorrect Ratio
P0731 on Jeep vehicles indicates gear 1 incorrect ratio. Au7o has documented this code across 1 Jeep model — most commonly on Grand Cherokee. This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 1st gear. The module compares input (engine/turbine) speed to output shaft speed; when the car is commanded into 1st but the calculated ratio doesn't match the expected value, P0731 sets. This points to slipping, an incorrect shift, or a hydraulic/mechanical problem rather than just an electrical fault. You may feel slipping, harsh or delayed engagement, or the transmission may go into a limited 'limp' mode. Typical repair costs on Jeep range from $300 to $3,500, depending on the specific model and root cause.
Common Causes of P0731
- •Low or degraded/burnt transmission fluid
- •Slipping clutch packs or worn friction components
- •Stuck or faulty shift solenoid affecting 1st gear
- •Internal hydraulic leak / valve body fault
- •Worn or failing torque converter
- •Faulty input or output speed sensor
- •Mechanical wear (planetary gears, bands) inside the transmission
P0731 on Jeep by Model
Jeep Grand Cherokee(1 issue)
- W5A580 (NAG1) 5-Speed Automatic Limp Mode and Harsh Shift from Conductor-Plate Speed Sensors and Fluid Contamination2005-2013
The Mercedes-derived W5A580 (NAG1) 5-speed automatic used in WK and early WK2 Grand Cherokees is mechanically strong but suffers well-documented electronic and fluid-related failures. Faulty conductor-plate speed sensors and shift-pressure solenoids drop the transmission into limp mode (stuck in a single gear). Contaminated or degraded fluid (including water intrusion past the dipstick/fill-tube seal) causes torque-converter-clutch shudder, harsh or delayed shifts, and a knock on coasting downshifts. The 13-pin connector adapter can also leak, wicking fluid into the harness by capillary action.
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What does P0731 mean on Jeep?▼
P0731 stands for "Gear 1 Incorrect Ratio." This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 1st gear. The module compares input (engine/turbine) speed to output shaft speed; when the car is commanded into 1st but the calculated ratio doesn't match the expected value, P0731 sets. This points to slipping, an incorrect shift, or a hydraulic/mechanical problem rather than just an electrical fault. You may feel slipping, harsh or delayed engagement, or the transmission may go into a limited 'limp' mode. On Jeep specifically, this code is documented across 1 model.
What causes P0731 on Jeep vehicles?▼
Common causes on Jeep: Low or degraded/burnt transmission fluid, Slipping clutch packs or worn friction components, Stuck or faulty shift solenoid affecting 1st gear, Internal hydraulic leak / valve body fault, Worn or failing torque converter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0731 on a Jeep?▼
Repair costs on Jeep range from $300 to $3,500, depending on the specific model and root cause.
Which Jeep models have P0731 documented?▼
Au7o has documented P0731 on 1 Jeep model: Grand Cherokee.