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(3 issues)
- 2004 545RFE Intermittent Low-Line-Pressure or Gear-Ratio DTCs — Check TCM Build Date2004
DaimlerChrysler TSB 08-016-05 describes an internal TCM circuit fault that may cause an intermittent low-line-pressure or gear-ratio DTC and limp-in on a specific 2004 WJ/WG Grand Cherokee population. The vehicle must have the 545RFE (sales code DGQ), a 4.7L or 4.7L High Output engine, and fall within the bulletin's April 7, 2004 through February 27, 2005 vehicle build range. Suspect TCMs have date codes 0984 through 0405. This is not a universal 1999-2010 transmission-overheating/shudder diagnosis, and it does not justify buying filters, fluid, a cooler, valve-body kits, or a solenoid pack from the symptom alone.
- Internal Radiator Transmission-Cooler Failure Cross-Contaminating ATF and Coolant ('Pink Milkshake')1999-2004
On the WJ the automatic-transmission fluid cooler is integrated inside the radiator end tank. As the radiator ages the internal cooler barrier fails, allowing engine coolant and ATF to intermix under pressure. The result is a pink/tan 'strawberry milkshake' in both the transmission and cooling system. Coolant (ethylene glycol) in the transmission destroys clutch material and can ruin the 42RE/45RFE if not caught quickly.
- 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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View P0731 across all makes →Frequently Asked Questions
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.