P0731 on 2024 Ram 2500: Gear 1 Incorrect Ratio Causes and Fixes

What's Unique About the 2024-2024 Ram 2500

The 2024 Ram 2500 can be equipped with several different transmissions, primarily the ZF 8-speed automatic for the 6.4L HEMI V8, and either the Chrysler 68RFE or the Aisin AS69RC 6-speed automatic for the 6.7L Cummins Turbo Diesel. TSB #21-012-25 REV. E specifically addresses P0731 on 2024 Ram 2500/3500 trucks with the 68RFE transmission built between June 14, 2024, and September 04, 2024, linking the code to a cracking rear selective thrust bearing, which necessitates a full transmission replacement. For previous model years with the Aisin transmission, this code was strongly associated with a specific internal failure of a K1 clutch snap ring, a well-documented issue that led to a loss of gears 1-4. This highlights that the specific transmission in the truck is critical for accurate diagnosis.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle hesitates or has delayed engagement from a stop.
• Harsh or abrupt shifting into or out of first gear, sometimes with a clunk.
• Transmission slipping (engine RPMs rise without an increase in speed).
• Vehicle enters "limp mode" (gets stuck in one gear).
🎬 Watch: A breakdown of common causes and fixes for P0731.
• Reduced fuel economy.
• Sensation of the transmission briefly returning to neutral before engaging first gear.
• Whining noise from the transmission.

Most Likely Causes

1. Low or Contaminated Transmission Fluid 🔴 High Probability → Shop Transmission Assembly Incorrect fluid levels prevent the hydraulic pressure needed to engage gears properly. Contamination from debris can clog passages in the valve body, a common cause for this DTC. A leaking transmission cooler in the radiator can also cause coolant to contaminate the transmission fluid, leading to low fluid levels and internal damage.
   How to confirm: Check the transmission fluid level and condition according to the manufacturer's procedure. The fluid should be at the correct level, red in color, and not smell burnt. Milky-looking fluid indicates coolant contamination.
   Typical fix: Top off the fluid if low and inspect for leaks. If the fluid is dirty, burnt, or contaminated, perform a fluid and filter change. Use the correct Mopar fluid (e.g., Mopar ZF 8&9 Speed ATF, Mopar 68RFE ATF, or Mopar Aisin AS69RC ATF).
   Est. part cost: $50-$200
2. Faulty Transmission Valve Body or Solenoids 🟡 Medium Probability → Shop Transmission Valve Body The 68RFE valve body is known for issues like cross-leaks between valve body halves and bore wear in the solenoid switch valve (SSV), which can lead to pressure loss and trigger ratio codes. The Low/Reverse switch valve can also wear and cause cross-leaks, specifically leading to P0731. 🎬 See a real-world diagnosis of a 68RFE ratio error.
   How to confirm: A technician can use a scan tool to command solenoids on and off and check for pressure drops. A physical inspection of the valve body for warpage or worn bores may be required. Specific resistance checks can be performed on the solenoids.
   Typical fix: Replacement of the faulty shift solenoid, the entire solenoid pack, or the complete valve body assembly.
   Est. part cost: $300-$1200
3. Transmission Control Module (TCM) Software Issue 🟡 Medium Probability → Shop Transmission Assembly Manufacturers often release software updates to correct shifting logic and address false codes. In some cases, incomplete software updates or data corruption in the TCM's gear-ratio tables can trigger a P0731 code.
   How to confirm: A dealership or qualified shop can check for available TSBs and determine if the TCM software is up to date using a wiTECH scan tool.
   Typical fix: Reprogramming (flashing) the TCM with the latest software.
   Est. part cost: $100-$300 (labor)
4. Internal Transmission Mechanical Failure ⚪ Low Probability → Shop Transmission Assembly For 2024 Ram 2500s with the 68RFE transmission built within a specific date range (June-Sept 2024), TSB 21-012-25 REV. E points to a cracking rear selective thrust bearing as the cause. In earlier models with Aisin transmissions, a failed K1 clutch snap ring was a known issue causing this code. Other failures include the Low/Reverse sprag, which can fail due to shock load during normal operation.
   How to confirm: This is usually diagnosed after all other possibilities (fluid, electronics, valve body) have been ruled out. It requires transmission disassembly. The diagnosis for TSB 21-012-25 REV. E is based on the VIN build date and the presence of the code.
   Typical fix: For the issue described in TSB 21-012-25 REV. E, the fix is a complete transmission replacement. For other internal failures, rebuilding or replacing the transmission is required.
   Est. part cost: $2500-$7000+

Rare But Worth Checking

• Faulty Input or Output Speed Sensor: While these sensors are used to detect the problem, they usually set their own specific codes when they fail (e.g., P0716). However, an intermittent sensor could potentially trigger P0731 without a dedicated sensor code.
• Fluid Drain-Back After Sitting: A user on the Turbo Diesel Register forum with a 2017 Ram 2500 experienced P0731 after the truck sat for a few weeks. Other members suggested that fluid may have drained back from the valve body, causing a delay in hydraulic pressure on startup.

Diagnosis Steps

1. Verify the code with a professional OBD-II scanner that can read transmission data.
2. Check the transmission fluid level and condition. Ensure it is clean, at the proper level, and does not smell burnt.
3. Check for any available Technical Service Bulletins (TSBs) for your vehicle's VIN, especially TSB 21-012-25 REV. E if you have a 2024 model with the 68RFE transmission. A software update or transmission replacement could be the required fix.
4. Use a scan tool to monitor live data from the input and output speed sensors while driving to see if they are reading correctly.
5. Check Event Data with a scan tool. Data showing the fault set with low line pressure can point to a hydraulic leak, while data showing it set in Park or Neutral could indicate a PCM issue.
6. Test the operation of the shift solenoids using the scan tool's command functions.
7. If other steps do not identify the issue, inspect the transmission valve body for debris or damage.
8. If all else fails, a more invasive inspection of internal transmission components may be necessary, as indicated for the K1 snap ring failure on Aisin models or the thrust bearing issue on 68RFE models.

Parts You'll Likely Need

• Transmission Fluid and Filter Kit — The first and most important step is to ensure the fluid is clean and at the correct level, as this is a very common cause of shifting problems.
  Trusted brands: Mopar
  OEM price range: $100-$200
  Aftermarket price range: $50-$120
• Transmission Valve Body (OEM #68448028AD (68RFE), 68445748AA (Aisin AS69RC)) — The valve body and its integrated solenoids are a frequent failure point that causes incorrect gear ratio codes. Part numbers vary by transmission type.
  Trusted brands: Mopar
  OEM price range: $800-$1600
  Aftermarket price range: $500-$1000
• Shift Solenoid / Solenoid Pack (OEM #Included with Valve Body (e.g., 68448028AD)) — A single faulty solenoid responsible for first gear can cause this code. Often, they are replaced as a pack or as part of the valve body assembly.
  Trusted brands: Mopar, RevMax
  OEM price range: $400-$600
  Aftermarket price range: $250-$450

Related Codes That Often Appear With This One

• P0732 — Incorrect Gear 2 Ratio. These codes often appear together as they point to a systemic issue within the transmission affecting multiple gears. TSB #21-012-25 REV. E lists them together.
• P0733 — Incorrect Gear 3 Ratio. Like P0732, this indicates a broader transmission problem. TSB #21-012-25 REV. E lists them together.
• P0734 — Incorrect Gear 4 Ratio. Another gear ratio error that points to a common cause. TSB #21-012-25 REV. E lists them together.
• P0729 — Incorrect Gear 6 Ratio. Also listed in TSB #21-012-25 REV. E, suggesting a related fault.
• P0716 — Input Speed Sensor 1 Circuit Performance. An issue with the speed sensor can cause the TCM to miscalculate gear ratios. This code is also mentioned in TSB #21-012-25 REV. E.
• P0868 — Transmission Fluid Pressure Low. This code indicates a hydraulic pressure issue, which is a root cause for gear ratio errors. It is also listed in TSB #21-012-25 REV. E.

Technical Service Bulletins (TSBs) & Recalls

• 21-012-25 REV. E: Lists P0731-00 for 2024 Ram trucks with the 68RFE transmission as a primary DTC for a known internal thrust bearing failure requiring transmission replacement.
• 21-002-23: (For prior model years with Aisin transmissions) Addressed P0731 caused by a K1 clutch snap ring failure, providing a specific repair kit (P/N 68637534AA) as the fix.

Platform-Specific Known Issues

• TSB #21-012-25 REV. E: For 2024 Ram 2500/3500 with the 68RFE transmission built between June 14 and Sept 4, 2024, this TSB identifies a cracking rear selective thrust bearing as the cause for P0731 and a host of other codes. The prescribed repair is transmission replacement.
• Aisin K1 Clutch Snap Ring Failure: On previous generation Ram HD trucks with the Aisin AS69RC transmission, P0731 was a very common indicator of a dislodged K1 clutch snap ring, leading to a loss of gears 1-4. This was addressed by TSB 21-002-23 for those model years.

Mechanic-Grade Diagnostic Values

• 68RFE Shift Solenoid Resistance (UD, OD, 4C, 2C, MS) — expected: 1.3 Ohms. Failure: An open circuit (infinite resistance) or a reading significantly different from 1.3 Ohms.
• 68RFE Pressure Control Solenoid Resistance — expected: 4.9 Ohms. Failure: An open circuit or a reading significantly different from 4.9 Ohms.
• 68RFE Input/Output Speed Sensor Resistance — expected: Approximately 535 Ohms at room temperature.. Failure: An open circuit or a reading far from the specification.
• 68RFE Stock Line Pressure (Scan Tool) — expected: Approx. 60 psi at idle in Drive, up to 160 psi under heavy load.. Failure: If DTC Event Data shows the P0731 code was set when actual line pressure was significantly below the desired line pressure, it indicates a hydraulic leak, bad filter seal, or failing pump.

Scan Tool Commands That Help

• wiTECH or equivalent professional scanner: TCM Quick Learn — This procedure must be performed after replacing the valve body, solenoid pack, or entire transmission, or after flashing the TCM, to allow the controller to learn the new components' hydraulic characteristics.
• wiTECH or equivalent professional scanner: Gear Ratio Test — To command the transmission to hold 1st gear and compare the live input and output speed sensor data against the specified ratio to confirm the slip is occurring in that specific gear.
• wiTECH or equivalent professional scanner: Line Pressure Test — To compare the 'Desired Line Pressure' PID with the 'Actual Line Pressure' PID under various loads. A large discrepancy can confirm a hydraulic pressure loss issue before disassembling components.

Wiring & Ground Locations

• Transmission 23-Way Connector — The main electrical connector on the transmission case of the 68RFE.. This connector carries all signals for the solenoids and sensors within the transmission. Corrosion or pushed-out pins in this connector can cause an open circuit for the Low/Reverse solenoid (Pin 2) or its power feed (Pin 10), directly leading to ratio codes.
• TCM Grounds — The TCM circuit board is grounded through specific wires in the harness connector, not by its case. These ground wires are often bundled into a welded splice within the main harness that can fail.. A poor ground for the TCM or its sensors can cause erratic readings and incorrect calculations, leading to false ratio codes. A forum user with multiple codes traced the issue to a failed ground splice in the ECM harness.

Real Owner Repair Stories

• RamForum.com user McGyverBob (2018 Ram 2500 with a heavily modified 68RFE transmission, 35k miles since rebuild.) — P0731 (Gear 1 Incorrect Ratio) would set only when the transmission was hot (above 125°F). Symptoms included a slip-and-slam engagement from a stop and hard shifting. The truck shifted perfectly when cold.
  ❌ Tried (didn't work) The transmission had already been rebuilt with numerous high-performance aftermarket parts, including an ATS valve body, RevMax solenoid pack, and DPC torque converter.
  ✅ What actually fixed it The user was still diagnosing, but expert advice on the forum pointed strongly toward two possibilities: 1) A failing torque converter (stator sprag or TCC piston) causing issues only when fluid thins out at temperature. 2) An internal hydraulic cross-leak in the valve body that only manifests when the metal components expand with heat. Both scenarios could cause a pressure loss to the 1st gear clutch pack, triggering the P0731 code only when hot.
• YouTube video by 'FSP Transmissions' (6.7L Ram 3500 with 68RFE transmission.) — P0731 code, neutraling out when stopping aggressively, then slamming back into gear. Also had a low coolant light.
  ❌ Tried (didn't work) The truck had a recently replaced transmission from another shop, so all internal electronics and solenoids were new.
  ✅ What actually fixed it The root cause was a leaking internal transmission cooler inside the radiator. This caused transmission fluid to be pushed into the cooling system (explaining the low coolant light and fluid in the reservoir) and lowered the transmission fluid level, starving it of fluid. The low fluid level was the direct cause of the slipping and P0731 code.

OEM Part Supersession History

• 52109091AA, 52109091AB, 68448028AA, 68448028AB, 68448028AC → 68448028AD — Progressive updates and revisions to the 68RFE valve body assembly by Mopar.
  Heads up: While the latest part number (68448028AD) is specified for 2019-2024 models, it's crucial to verify fitment with a VIN as mid-year changes can occur.

Model Year Variations Within This Range

• 2024 (Build dates June 14, 2024 - September 04, 2024): Vehicles with the 68RFE transmission built in this specific timeframe are subject to TSB 21-012-25 REV. E, which identifies a faulty rear selective thrust bearing as the cause for P0731 and other ratio codes. The prescribed fix is a complete transmission replacement.