P0933 on 2014-2020 Ram 2500: Hydraulic Pressure Sensor Causes and Fixes

What's Unique About the 2014-2020 Ram 2500

For Ram 2500 trucks equipped with the common 68RFE automatic transmission, this code is a well-documented issue. The hydraulic pressure sensor, also called a transducer, is integrated into the main solenoid pack, which is a known failure point. Multiple manufacturer Technical Service Bulletins (TSBs) list P0933, confirming it's a recognized problem across many model years. Owners and technicians on forums like Cummins Forum and HD Rams frequently report that replacing the entire solenoid pack is the definitive fix, often after aftermarket or individual sensor replacements fail. A user on Turbo Diesel Register noted their scan tool showed the pressure stuck at 252psi on a cold start, which immediately triggered the code.

Diagnostic Flowchart

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

Generation note: This range covers the end of the third generation (2014-2018) and the start of the fourth generation (2019-2020) Ram 2500. Both generations commonly used the 68RFE automatic transmission with the 6.7L Cummins engine, where this issue is most prevalent. A significant change occurred in 2019: the 68RFE solenoid pack was updated (identifiable by a blue vs. the older gray connector) and electronically coded to the vehicle's ECM. These parts are not interchangeable. 2019+ models require a scan tool relearn procedure after replacement.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle enters 'limp mode' (stuck in one gear, often 4th)
• Harsh, erratic, or delayed gear shifts
• Transmission slipping between gears
• Reduced acceleration or poor throttle response
• A jump or lurch when first putting the truck into Drive

Most Likely Causes

1. Faulty Hydraulic Pressure Sensor (Transducer) 🔴 High Probability The sensor is integrated into the transmission solenoid pack, which is a widely documented failure point on the 68RFE transmission. The sensor itself fails and sends incorrect pressure readings to the TCM. Aftermarket sensors are particularly known for high failure rates.
   How to confirm: Use a high-quality scan tool (like AlfaOBD) to monitor live transmission data. Compare 'Desired Line Pressure' and 'Actual Line Pressure'. At idle in Park, a healthy sensor should show actual pressure closely matching desired pressure (typically around 60 PSI, with a variance of less than 5 psi). If the actual pressure reading is stuck (e.g., at 252 psi), erratic, or does not increase with engine RPM, the sensor is bad.
   Typical fix: Replace the entire transmission solenoid pack assembly. It is highly recommended to use a genuine Mopar part, as aftermarket units have a high failure rate. For 2019+ models, this is mandatory as the part is coded to the vehicle.
   Est. part cost: $400-$550
2. Low or Degraded Transmission Fluid 🟡 Medium Probability The 68RFE is sensitive to fluid level and condition. A user on the Ram Heavy Duty Forum reported getting P0933 and P0871 codes after a fluid change because the fluid level was too low, causing pressure issues.
   How to confirm: Check the transmission fluid level using the dipstick (engine running, in neutral, on a level surface). Inspect the fluid's condition; it should be bright red and not smell burnt. Dark, burnt-smelling fluid indicates internal wear.
   Typical fix: Perform a transmission fluid and filter change using Mopar ATF+4 fluid. A standard pan drop and filter change requires approximately 7-8 quarts of fluid.
   Est. part cost: $100-$180
3. Wiring or Connector Issues ⚪ Low Probability The main transmission electrical connector on the driver's side of the case is exposed to the elements. Corrosion inside the connector, which may be hidden under the yellow cap, can disrupt the sensor signal and cause erratic readings.
   How to confirm: Unplug and carefully inspect the main transmission connector for any signs of corrosion (green or white powder), moisture, or bent/damaged pins. A Reddit user with persistent P0933 and P0935 codes was advised to specifically check the ground control circuit on the main harness.
   Typical fix: Clean the connector terminals with an electrical contact cleaner. If corrosion is severe, the connector pigtail may need to be replaced. Apply dielectric grease during reassembly to prevent future moisture intrusion.
   Est. part cost: $20-$100

Rare But Worth Checking

• Failing Transmission Control Module (TCM): This is very rare. The TCM should only be considered after all other possibilities, including the sensor, fluid, and wiring, have been definitively ruled out.
• Internal Hydraulic Leak or Blockage: A stuck pressure regulator valve in the pump or a major internal leak can cause pressure control problems, but this is less common than a sensor failure and usually accompanied by more severe symptoms like significant clutch slippage.

Diagnosis Steps

1. Check and verify the transmission fluid is at the correct level and in good condition. Ensure the truck is in neutral on a level surface with the engine running.
2. Use a capable scan tool (e.g., AlfaOBD, wiTECH) to read all DTCs from the TCM. Note any other codes that are present.
3. Monitor the 'Desired Line Pressure' and 'Actual Line Pressure' PIDs with the scan tool. Observe the actual pressure reading at idle, and while gently increasing engine RPM in neutral. A healthy sensor should show pressure increasing with RPM and closely tracking the desired value.
4. If the actual pressure reading is stuck (often at 252 psi), erratic, or reads significantly higher than desired pressure at idle, the sensor is faulty.
5. If the sensor data seems plausible, inspect the main transmission electrical connector on the driver's side of the transmission for any signs of corrosion, damage, or loose pins. Pay close attention to the area under the yellow cap.
6. If the wiring is confirmed to be good and the fluid level is correct, the hydraulic pressure sensor (within the solenoid pack) is the primary suspect.
7. As a final verification, a mechanical pressure gauge can be connected to the transmission's line pressure port using a special adapter (like Miller tool #8259) to compare the mechanical reading with the sensor's electronic reading.

Parts You'll Likely Need

• Transmission Solenoid Pack Assembly (OEM #68376695AA (supersedes 68353383AB for 2014-2018 models with gray connector). 2019+ models use a different part with a blue connector.) — This assembly contains the integrated hydraulic pressure sensor (transducer), which is the most common point of failure for code P0933 on the 68RFE transmission.
  Trusted brands: Mopar, Revmax, SunCoast
  OEM price range: $400-$550
  Aftermarket price range: $250-$400

Related Codes That Often Appear With This One

• P0868 — Stands for 'Transmission Fluid Pressure Low'. A failing sensor can give erratic readings, sometimes low, triggering this code. TSB #18-069-25 explicitly links P0933 and P0868.
• P0869 — Stands for 'Line Pressure High'. This is a very common companion code, as the sensor often fails by reporting a pressure reading that is too high.
• P0934 — Stands for 'Line Pressure Sensor Circuit Low'. This points to a specific electrical fault (like a short to ground) in the sensor's circuit.
• P0935 — Stands for 'Line Pressure Sensor Circuit High'. This points to an open circuit or short to power. Some owners report this code appears if the truck is restarted after P0933 has already been set.
• P0735 / P0729 — Incorrect gear ratio codes for 5th and 6th gear. TSB #18-069-25 notes that the incorrect line pressure caused by the P0933 fault can lead to clutch slippage, which in turn triggers these ratio errors.

Technical Service Bulletins (TSBs) & Recalls

• 18-069-25: Links P0933 with other codes like P0868 (Pressure Low) and gear ratio errors, pointing to a common underlying cause.
• 18-091-16: Lists P0933 as a potential Diagnostic Trouble Code related to the electrical system and transmission performance.
• 18-057-15 REV A: Includes P0933 in a list of transmission-related diagnostic trouble codes.
• 1803014REVB: Mentions P0933 in the context of power train issues.
• 21-016-17: Details diagnosis for water intrusion and corrosion at the transmission's 16-way connector, which can be a root cause for P0933.

Platform-Specific Known Issues

• 2019+ Solenoid Pack is Electronically Coded: Starting in 2019, the 68RFE received an updated solenoid pack (blue connector) that is electronically matched to the vehicle's ECM/TCM. You cannot use a pack from another vehicle or an aftermarket unit without performing a specific scan tool relearn procedure (PI Curve Reset). For most owners, this means an OEM part is required.
• Real Owner Experience (2015 Ram 2500): A user on the Turbo Diesel Register forum with a 2015 Ram 2500 at 44,000 miles experienced codes P0933, P0869, and P0935. On a cold start, his scan tool showed the line pressure was stuck at 252 psi. After confirming the wiring and fluid were good, the problem was resolved by replacing the entire solenoid pack with a new Mopar unit.
• Real Owner Experience (2018 Ram): A Reddit user with a 2018 Ram was getting P0933 and P0935 even after replacing the valve body, sensors, and solenoid pack. This points to a more elusive wiring issue, with others suggesting a detailed check of the ground control circuit in the main harness.

Mechanic-Grade Diagnostic Values

• Line Pressure Sensor Voltage (Normal Operation) — expected: 0.35V to 4.75V. Failure: Voltage below 0.35V (sets P0934) or above 4.75V (sets P0935).
• Line Pressure Solenoid Resistance — expected: Approx. 4.0 - 4.3 Ohms. Failure: Significantly higher or lower resistance, or an open circuit.
• Line Pressure Solenoid Current Draw (Max) — expected: Approx. 1 Amp. Failure: Inability to draw max current may indicate a solenoid or driver issue, though a full 1A draw confirms circuit integrity.
• Line Pressure Sensor Signal Wire Voltage (at idle) — expected: Approx. 0.5V. Failure: A reading of 4.9V or higher indicates a circuit high fault.
• Scan Tool vs. Mechanical Gauge Pressure — expected: Readings should be within 34 kPa (5 psi) of each other.. Failure: A significant difference between the scan tool reading and the mechanical gauge confirms the sensor is inaccurate.

Scan Tool Commands That Help

• wiTECH or AlfaOBD: Quick Learn — This procedure must be performed after replacing the solenoid pack, valve body, or TCM to allow the transmission to recalibrate clutch fill volumes and shift points.
• wiTECH with Miller Tool #8333: Transmission Simulator Test — This is an advanced dealer-level test to isolate the PCM from the transmission harness. It simulates sensor inputs to verify if the PCM is responding correctly, helping to rule out a faulty PCM.

Wiring & Ground Locations

• Line Pressure Sensor Connector — On the passenger side of the transmission case, sometimes behind a heat shield.. This is the direct connection to the sensor. Checking for 5V supply, ground, and signal voltage here is a primary diagnostic step.
• PCM Connector C4, Pin T38 — At the Powertrain Control Module (PCM).. This is the Line Pressure Sensor Signal circuit pin. Testing for continuity on this wire between the sensor and the PCM can identify an open or shorted wire in the harness.
• PCM Connector C2, Pin T160 — At the Powertrain Control Module (PCM).. This is the Sensor Ground circuit pin. A resistance test on this wire can identify an open ground, which can cause high voltage readings.
• Solenoid/TRS Assembly Connector (C107) — The main round connector on the driver's side of the transmission case.. This connector carries all signals for the solenoid pack. Corrosion or spread pins here can cause P0933 and other transmission codes. Pin 12 is the Pressure Control Solenoid Control circuit.

Real Owner Repair Stories

• Reddit user u/thesose67 (2018 Ram 2500) — Persistent P0933 code, which would be joined by P0935 if the codes were not cleared before restarting the truck.
  ❌ Tried (didn't work) Replaced valve body with an ATS performance unit, Replaced the pressure sensor, Replaced the shift solenoid with a Revmax unit, Installed a deep pan and thermal bypass
  ✅ What actually fixed it The user suspected a wiring issue after all part replacements failed, specifically mentioning advice to check the 'PCS Line Pressure Solenoid PM Ground Control Circuit' on the main harness. The final resolution was not posted, but the story highlights that extensive parts replacement may not solve a persistent wiring fault.
• Turbo Diesel Register user Larry Willard (Year not specified, 68RFE transmission) — Intermittently not shifting past 4th gear, sometimes would eventually shift to 5th and 6th. No CEL, but stored codes P0933 and P0868 were found by the dealer.
  ❌ Tried (didn't work) Checked wiring connections, Changed transmission filters twice
  ✅ What actually fixed it The dealer replaced the line pressure sensor (part # 4799758AD). The truck worked perfectly for 700+ miles after the repair.

OEM Part Supersession History

• 68353383AB → 68376695AA — Updated Mopar part for the solenoid pack assembly.
  Heads up: For 2007.5-2018 models with a gray or white connector. Do not use on 2019+ models.
• Unknown → 68456067AA — New part for the updated 2019+ 68RFE design.
  Heads up: For 2019+ models ONLY. This part has a blue connector and is not interchangeable with the earlier gray/white connector packs.

Model Year Variations Within This Range

• 2019-2020: The 68RFE transmission was updated with a new valve body and solenoid pack. The new solenoid pack is identified by a blue electrical connector, whereas earlier models used a gray or white connector. The parts are not interchangeable, and the blue connector solenoid pack (e.g., Mopar #68456067AA) must be used for 2019+ trucks.