P0712 on 2010-2018 Ram 2500 6.7L Cummins: Transmission Temp Sensor Causes and Fixes

What's Unique About the 2010-2018 Ram 2500

On the Ram 2500 with the 6.7L Cummins engine, the automatic transmission is the Chrysler-built 68RFE. A key characteristic of this transmission is that the fluid temperature sensor is not a separate, easily replaced part. Instead, it is integrated directly into the main transmission solenoid pack (also called the solenoid block or valve body) located inside the oil pan. This design means that a simple sensor failure requires the replacement of the entire, more expensive solenoid assembly. It's critical to identify the correct solenoid pack, as 2011-2018 models typically use a grey connector, while earlier or later models may differ.

Generation note: The 2010-2018 model years span the end of the third generation (2010) and the entire fourth generation (2011-2018) Ram 2500. Both generations used the 68RFE transmission with the 6.7L Cummins engine, and the causes and fixes for P0712 are consistent across this range. Service parts like the solenoid pack are generally compatible, but it's crucial to verify the connector color (white vs. grey) before purchasing.

Symptoms You May Notice

• Check Engine Light is on
• Transmission may go into 'limp mode' (stuck in one gear)
• Harsh, erratic, or delayed gear shifts.
• Transmission temperature warning light may be illuminated.
• Torque converter clutch may fail to engage or lock up improperly.
• Transmission may feel like it's slipping between gears.

Most Likely Causes

1. Failed Transmission Temperature Sensor (Internal to Solenoid Pack) 🔴 High Probability The solenoid pack is a known failure point on the 68RFE transmission due to constant heat cycles and exposure to fluid contaminants which can get into the solenoids. The integrated sensor fails, creating a short circuit that results in the P0712 code.
   How to confirm: Use a diagnostic scan tool to monitor the live data for Transmission Fluid Temperature. A reading that is stuck at an extremely low value (e.g., -40°F) even when the engine is warm confirms a sensor/circuit fault.
   Typical fix: Drop the transmission oil pan and replace the entire solenoid pack assembly. 🎬 See this DIY walkthrough for installing a new valve body A transmission fluid and filter change is required as part of the job. A "Quick Learn" procedure should be performed with a scan tool after replacement.
   Est. part cost: $350-$600
2. Wiring Harness or Connector Issue 🟡 Medium Probability The wiring harness leading to the transmission is exposed to road debris, heat, and moisture, which can lead to chafing, corrosion, or wires shorting to the chassis ground. A known problem area is the large multi-pin connector on the driver's side of the transmission case, which can suffer from corrosion or pushed-back pins.
   How to confirm: Visually inspect the wiring harness from the transmission connector back to the control module for any signs of damage, melting, or corrosion. Perform a continuity test on the sensor signal wire to check for a short to ground. Wiggling the harness while monitoring live data can also reveal intermittent shorts.
   Typical fix: Repair or replace the damaged section of the wiring harness. Clean or replace the transmission electrical connector if it is corroded.
   Est. part cost: $20-$200
3. Outdated Powertrain Control Module (PCM) Software ⚪ Low Probability Ram issued multiple Technical Service Bulletins (e.g., TSB 18-030-14) indicating that some transmission fault codes, including P0712, could be triggered unnecessarily due to overly sensitive software logic. An update can change the fault from a one-trip to a two-trip trigger, preventing false positives.
   How to confirm: A Ram dealership or a properly equipped independent shop can check your vehicle's VIN against TSBs and see if a software update is available.
   Typical fix: Reprogram (flash) the PCM/TCM with the latest manufacturer software. This should be done before replacing expensive hardware.
   Est. part cost: $0-$200

Rare But Worth Checking

• Failed Powertrain/Transmission Control Module (PCM/TCM): While rare, the control module itself can fail, causing an internal short on the sensor's input circuit. This should only be considered after the sensor, wiring, and software have all been confirmed to be good.

Diagnosis Steps

1. Connect a capable OBD-II scanner and check for any other transmission-related codes.
2. View the live data stream for the Transmission Fluid Temperature (TFT) sensor. If the truck is cold, the TFT reading should be very close to the ambient air and engine coolant temperature readings (within 5-7°F).
3. If the TFT reading is stuck at a very low number (like -40°F), it strongly suggests a circuit low fault.
4. Check with a dealer or qualified shop to see if any PCM software updates related to TSBs like 18-030-14 are available for your vehicle. Perform updates before replacing parts.
5. Thoroughly inspect the transmission wiring harness and the main 23-way electrical connector on the driver's side of the transmission for any signs of physical damage, corrosion, or loose pins.
6. Disconnect the harness and use a multimeter to test for a short to ground on the sensor signal wire (Pin 23 or Pin 8, depending on the specific diagram). A resistance reading of 100 k/ohms or less indicates a short.
7. If the wiring appears intact and software is up to date, the fault is most likely the internal temperature sensor, which requires replacing the transmission solenoid pack.

Parts You'll Likely Need

• Transmission Solenoid Pack (Block) (OEM #68353383AB (supercedes earlier part numbers, verify connector color)) — This is the most common cause of P0712, as the temperature sensor is integrated into this assembly on the 68RFE transmission. Models from 2011-2018 typically use the 'grey connector' version.
  Trusted brands: Mopar, Sonnax, Rostra, RevMax
  OEM price range: $450-$600
  Aftermarket price range: $350-$500
• Automatic Transmission Fluid (ATF+4) (OEM #68218057AC (or equivalent)) — Required when dropping the transmission pan to replace the solenoid pack. Typically requires 7-9 quarts for a pan drop and refill. Using the correct ATF+4 fluid is critical for 68RFE longevity.
  Trusted brands: Mopar, Valvoline, Castrol
  OEM price range: $12-$18 per quart
  Aftermarket price range: $8-$12 per quart
• Transmission Filter Kit (OEM #68019688AA (or kit equivalent)) — Should always be replaced when the transmission pan is removed. The 68RFE has two filters: a spin-on filter and a sump filter (pan filter).
  Trusted brands: Mopar, Wix, ATP
  OEM price range: $50-$80
  Aftermarket price range: $30-$60

Related Codes That Often Appear With This One

• P0711 — This code for 'Transmission Temperature Sensor Performance' often appears with P0712 because a shorted sensor provides illogical or irrational readings that don't change over time as expected.
• P0713 — This code for 'Transmission Temperature Sensor High' can appear if the wiring has an intermittent short or open, causing the voltage signal to fluctuate wildly between its lowest and highest possible values.
• P0700 — This is a generic transmission fault code requested by the TCM. It simply means the TCM has stored a fault (like P0712) and has illuminated the Check Engine Light.

Technical Service Bulletins (TSBs) & Recalls

• 18-030-14 - Addresses unnecessary Malfunction Indicator Lamp (MIL) illumination for several transmission faults, including P0712, P0713, and P0714.

Platform-Specific Known Issues

• Owners on the Turbo Diesel Register forum report normal operating temperatures for the 68RFE transmission to be between 160-185°F during highway cruising, with temperatures potentially rising when towing heavy loads. A reading of -40°F is a definitive sign of a sensor circuit fault.
• The 68RFE is generally considered reliable for stock power levels but can be a weak point when the 6.7L Cummins engine is modified for higher torque output.

Mechanic-Grade Diagnostic Values

• Transmission Temperature Sensor (TFT) vs. Intake Air Temperature (IAT) on cold soak — expected: Within 5-7°F of each other. Failure: A significant difference, or a TFT reading at its minimum (-40°F), points to a sensor or circuit fault.
• TFT sensor circuit voltage check (Key On, Engine Off) — expected: Approximately 5.0 volts on the reference wire. Failure: A reading significantly below 5.0V indicates a short or wiring issue.
• Resistance test for short-to-ground on TFT signal wire — expected: More than 100 k/ohms. Failure: 100 k/ohms or less indicates a short to ground in the harness.
• Resistance of individual solenoids in the 68RFE pack — expected: 1.3 Ohms for most shift solenoids; 4.9 Ohms for the Pressure Control solenoid.. Failure: Readings significantly outside these values, or an open circuit (OL), indicate a failed solenoid.

Scan Tool Commands That Help

• wiTECH (or equivalent high-level scan tool): Quick Learn — This procedure is mandatory after replacing the solenoid pack or valve body. It resets clutch volume index (CVI) adaptive values, allowing the TCM to relearn clutch fill times for smooth shifting.
• wiTECH (or equivalent): Reset Adaptive Values — Used as part of the Quick Learn procedure or to address customer complaints of poor shift quality. This clears the memory cells where the TCM stores learned shift timing information.

Wiring & Ground Locations

• Transmission 23-Way Connector — On the driver's side of the 68RFE transmission case.. This is the main connection point for all transmission electronics. P0712 diagnosis requires testing pins here. Pin 23 is the TFT Sensor Signal and Pin 22 is the Sensor Ground according to one source. Another source indicates Pin 8 for the signal and Pin 3 for the ground. Technicians should verify with a vehicle-specific diagram.
• Main Chassis Ground — A critical ground point is located on the firewall in the rear driver's side of the engine bay, connecting to a module behind the air cleaner.. While not specific to the P0712 circuit, poor grounds are a known cause of various electronic and transmission shifting issues on these trucks due to corrosion between the steel ring terminal and aluminum body.

Real Owner Repair Stories

• eBay Seller Listing (2007-2018 Dodge Ram with 68RFE) — Not specified, but the owner was prepared to replace the solenoid pack.
  ❌ Tried (didn't work) The owner purchased a new solenoid pack, assuming it was the cause.
  ✅ What actually fixed it The owner discovered a broken cable on the transmission connector. Repairing the wire resolved the issue without needing to replace the solenoid pack.

When the Usual Fixes Don't Work

• While the solenoid pack is the most common failure, it is not always the cause. In one documented case, an owner purchased a solenoid pack to fix the issue but discovered the actual problem was a broken wire at the transmission connector. This highlights the critical importance of thoroughly testing the wiring harness for shorts to ground or open circuits between the TCM and the transmission connector before ordering and replacing the expensive internal solenoid pack.

OEM Part Supersession History

• Various (Black Connector, pre-2007.5) → Various (White Connector, e.g., Mopar 68353383AC) — Redesign of internal solenoids and transmission range sensor plate.
  Heads up: The white connector solenoid pack (2007.5-2010) is forward-compatible and can be used in 2011-2018 trucks.
• White Connector Solenoid Pack → Grey Connector Solenoid Pack (e.g., Mopar 68353383AB) — Internal redesign, one less solenoid used in the hydraulic circuit.
  Heads up: The grey connector solenoid pack (2011-2018) is NOT backward-compatible and cannot be used in 2007.5-2010 models.
• Grey Connector Solenoid Pack → Blue Connector Solenoid Pack (e.g., Mopar 68456067AA) — Further design changes for the newer generation of Ram trucks.
  Heads up: The blue connector pack is for 2019+ models and is not compatible with the 2010-2018 generation.

Model Year Variations Within This Range

• 2010 vs 2011-2018: The transmission solenoid pack connector changed. 2010 models use a white connector. 2011-2018 models use a grey connector. While the grey connector pack cannot be used on a 2010 model, the white connector pack CAN be used on 2011-2018 models, making it a universal service part for this generation.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Front End 'Death Wobble' 🔴 High — Common, especially on lifted trucks or after hitting a bump at highway speeds (45-65 mph). Can occur at any mileage due to wear on steering components. (Ref: No specific recall, but numerous TSBs exist for steering dampers and linkage components on various model years. The issue stems from worn parts like the track bar, ball joints, or tie rods.)
• EGR Cooler and Valve Clogging 🟠 Medium — Frequent, especially on trucks that see a lot of short trips or idling, preventing proper regeneration. Problems can start as early as 60,000-80,000 miles. (Ref: Multiple TSBs exist for EGR system diagnostics and cleaning procedures. The primary cause is soot buildup from the diesel combustion process.)
• Variable Geometry Turbo (VGT) Actuator Failure 🟠 Medium — Common failure point, often occurring between 80,000 and 150,000 miles. The electronic actuator can seize from heat and soot, causing loss of power or a stuck exhaust brake.
• Radiator End Tank Seepage/Leaks 🟠 Medium — A known issue where the plastic end tanks crimped to the aluminum core begin to leak coolant under pressure, often after 100,000 miles. It may start as a slow leak that is hard to notice.
• Grid Heater Bolt Failure 🔴 High — Less common but catastrophic. The bolt holding the grid heater can break off and fall into the intake manifold, potentially destroying the engine (typically cylinder #6).

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used solenoid pack is generally not recommended. The part has a known failure rate and can be contaminated with debris from the donor transmission, leading to a repeat failure. Given the labor involved in dropping the pan, a new part is a much safer investment.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the connector color matches the required part (white or grey).
• Inspect the electrical connector pins for any corrosion or damage.
• Check the filter screen on the bottom for excessive metallic debris, which indicates the donor transmission was failing.

OEM-only on this vehicle (don't cheap out):

• While not strictly 'OEM-only', using a genuine Mopar solenoid pack is the most recommended and reliable option for a stock vehicle.

Aftermarket brands forum-validated for this vehicle:

• Sonnax (often for upgraded internal components and valve bodies)
• RevMax
• Rostra

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost solenoid packs from online marketplaces are a significant risk and may fail prematurely.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0713 — Transmission Fluid Temperature Sensor 'A' Circuit High. This code is the direct counterpart to P0712, indicating an open circuit or a sensor reading that is too high. It points to a failure in the same sensor or wiring harness. TSB 18-030-14 also addresses this code.
• P0714 — Transmission Fluid Temperature Sensor 'A' Circuit Intermittent. This code is set when the PCM detects erratic or unstable signals from the temperature sensor. It's often caused by a loose connection, corroded pin in the connector, or a chafed wire—all of which are also potential root causes for P0712.

Frequently Asked Questions