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2022 Ram 3500 Transmission Limp Mode - P0700 and P0731 Codes

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Robert C. · rep 0 · May 22, 3:30 AM · 1 replies · solved · Question

Vehicle: 2022 Ram 3500 Limited

My 2022 Ram 3500 Limited, 6.7L Cummins, just went into limp mode on me. The check engine light is on, and it feels like it's stuck in a single gear, probably 3rd. I scanned it, and I'm getting P0700 (Transmission Control System Malfunction) and P0731 (Gear 1 Incorrect Ratio).

This happened suddenly while driving, no prior warnings. The truck has about 45,000 miles on it. I'm really hoping this isn't a major transmission rebuild. Could it be a sensor, or something simpler?

What should I check first? Is there a common issue with the 68RFE transmission that causes these codes?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:30 AM

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ClearTheCode admin answer:

Experiencing limp mode with P0700 and P0731 codes on your 2022 Ram 3500 6.7L Cummins (likely equipped with the 68RFE transmission) indicates a significant issue within the transmission's control or mechanical components. The P0700 is a generic code that tells you the Transmission Control Module (TCM) has detected a fault, and the P0731 specifically points to an incorrect gear ratio for 1st gear.

Here's a breakdown of potential causes and diagnostic steps:

  1. Check Transmission Fluid Level and Condition: This is always the first step. Park on a level surface, warm up the transmission, and check the fluid level according to your owner's manual. Low fluid can cause pressure issues and incorrect gear ratios. Also, inspect the fluid for burnt smell or dark color, which can indicate internal wear.
  2. Transmission Solenoid Pack/Valve Body: The 68RFE transmission is known for issues with its solenoid pack or valve body. These components control the hydraulic pressure to engage different gears. A faulty solenoid for 1st gear or a problem within the valve body could easily cause the P0731 code and limp mode.
  3. Transmission Speed Sensors: The input and output speed sensors provide crucial data to the TCM for gear ratio calculation. If one of these sensors is faulty or sending incorrect signals, the TCM might incorrectly determine the gear ratio, triggering the P0731 code. While less common for a sudden failure, it's worth considering.
  4. Wiring Harness Issues: Inspect the transmission wiring harness for any signs of damage, chafing, or loose connections. A compromised wire can interrupt signals to or from the TCM or solenoids.
  5. Internal Transmission Damage: Unfortunately, an incorrect gear ratio can sometimes point to internal mechanical failure, such as worn clutches, planetary gears, or a broken band. This is a more severe scenario.

When to See a Shop:

  • Immediately, if the truck is in limp mode. Driving extensively in limp mode can cause further damage to the transmission.
  • If the transmission fluid level and condition are good, but the codes persist.
  • If you suspect a solenoid pack or valve body issue, as these require specialized tools and expertise to diagnose and replace correctly.
  • Any time you have transmission-related codes that put the vehicle in limp mode, it's best to have it professionally diagnosed. A transmission specialist can perform advanced diagnostics, including pressure tests and internal inspections, to accurately determine the root cause and recommend the appropriate repair, which could range from a sensor replacement to a transmission overhaul.
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