P0733 on 2020-2023 Chrysler 300: Gear 3 Incorrect Ratio Causes and Fixes

What's Unique About the 2020-2023 Chrysler 300

The Chrysler 300 in this year range uses a ZF-designed 8-speed automatic transmission (often the 850RE, sales code DFT). While it's a sophisticated and generally robust unit, it has a well-documented pattern failure that causes the P0733 code. Chrysler has acknowledged a specific weakness in the 'D' clutch assembly and issued multiple Technical Service Bulletins (TSBs) that detail a specific repair procedure using an updated clutch kit. This is critical because it means a full, costly transmission replacement is explicitly NOT required to fix this common issue. The failure is often attributed to a thin, stamped OE backing plate in the clutch pack that flexes, causing uneven wear and eventual slippage.

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
• Transmission slipping or hesitating when shifting.
• Harsh or jerky shifts, sometimes described as a 'clunk'.
• Vehicle enters 'limp mode' (gets stuck in a single gear, often 2nd or 3rd).
• Failure to shift into or out of 3rd gear.
🎬 Watch: Understanding the causes and fixes for the P0733 code.
• Vehicle will not shift higher than third gear.
• Engine RPMs are higher than usual for a given speed (flaring).
• Vehicle will not move in reverse (in some cases).
• Delayed or poor acceleration.

Most Likely Causes

1. Internal Failure of the 'D' Clutch Assembly 🔴 High Probability Chrysler has issued multiple TSBs (e.g., 21-009-25) specifically for this failure on this transmission family. The original clutch hub was made of a material prone to wear from the steel clutch plates. More specifically, the OE backing plate is thin and stamped, allowing it to flex and bow, which causes uneven wear and leads to clutch burnup.
   How to confirm: Diagnosis is confirmed by the presence of code P0733, often accompanied by P1DA8-00 and/or P1D92-00, on a vehicle with over 7,000 miles, as specified in the TSB. A key diagnostic step for a technician is to perform a clutch air pressure test on the D-clutch circuit after removing the valve body; a failure confirms the internal leak.
   Typical fix: Replace the 'D' clutch assembly using the specific repair kit and procedure detailed in Chrysler TSB 21-009-25. 🎬 See how the updated D clutch parts fix this transmission. This is an internal transmission repair. After the mechanical repair, a mandatory 'TCM Adaptation Procedure' must be performed with a diagnostic tool.
   Est. part cost: $400-$800
2. Low or Degraded Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly While less likely to be the root cause given the known TSB, low fluid levels can cause low hydraulic pressure, leading to clutch slippage and ratio errors in any automatic transmission. A fluid change alone is highly unlikely to fix a recurring P0733 if the mechanical D-clutch has already failed.
   How to confirm: A physical check of the transmission fluid level and condition by a qualified technician. The 8-speed transmission is a 'sealed' unit without a dipstick, so this is not a simple driveway check and requires a specific procedure at a certain fluid temperature (30°C-50°C).
   Typical fix: Perform a transmission fluid and filter service, refilling with the correct Mopar ZF 8&9 Speed ATF. The filter is typically integrated into the oil pan. If fluid is dark or smells burnt, it's a symptom of the clutch failure, not the cause.
   Est. part cost: $150-$300

Rare But Worth Checking

• Faulty Valve Body or Shift Solenoid: → Shop Transmission Valve Body A solenoid can stick or fail, causing incorrect hydraulic pressure for a specific gear. While possible, the TSB for the D-clutch makes this a much less likely primary cause for this specific code on this vehicle. TSB S2621000003 REV. A notes that if the D-clutch repair does not resolve the issue, a valve body replacement should be considered next.
• Faulty Transmission Speed Sensor: → Shop Transmission Assembly If the input or output speed sensors provide incorrect data to the TCM, it can miscalculate the gear ratio and trigger the code. This is an uncommon cause for this specific platform issue.
• TCM Software Issue (2020 models): For some 2020 Ram 1500s (a platform mate) built on or before Nov 04, 2019, TSB 21-007-20 was released for P0733 occurring in 4-Lo range. The fix was a TCM software reprogram, not a mechanical repair. While less likely for the 300, it's a possibility for early 2020 models.

Diagnosis Steps

1. Scan the TCM for all stored diagnostic trouble codes. Note if P1DA8-00 or P1D92-00 are present with P0733.
2. Check for and review applicable Technical Service Bulletins, specifically TSB 21-009-25 and its revisions (A, B, C, etc.).
3. Verify the transmission fluid level and condition. This must be done by a technician, as there is no dipstick. Dark, burnt, or metallic fluid is a strong indicator of the D-clutch failure.
4. If fluid is correct and TSBs apply (especially on vehicles with over 7,000 miles), the diagnosis points strongly to the internal 'D' clutch failure.
5. For definitive confirmation before disassembly, a technician can remove the valve body and perform a clutch air pressure test on the D-clutch hydraulic circuit to check for leaks, as detailed in Chrysler's service procedures.
6. If TSBs do not seem to apply, proceed with traditional diagnostics, such as testing shift solenoids and verifying speed sensor data with a professional scan tool.

Parts You'll Likely Need

• 'D' Clutch Assembly Repair Kit (OEM #68527968AA) — This is the specific Mopar kit required to perform the repair outlined in TSB 21-009-25, containing the updated clutch components. Note: Some owners have reported kits arriving with missing seals, so inspection upon receipt is recommended.
  Trusted brands: Mopar
  OEM price range: $400-$700
• Transmission Oil Pan with Integrated Filter (OEM #68225344AA) — The pan must be removed for the repair, and the integrated filter must be replaced to remove contaminants from the clutch failure. The TSB notes to inspect the gasket for reuse, but if it is cut or torn, it must be replaced.
  Trusted brands: Mopar, ZF
  OEM price range: $150-$250
  Aftermarket price range: $100-$180
• Mopar ZF 8&9 Speed ATF (OEM #68218925AB) — This is the required fluid for refilling the transmission after the repair is completed. Approximately 4-5 quarts are needed for a service fill.
  Trusted brands: Mopar
  OEM price range: $25-$40 per quart
• Heavy Duty 'D' Clutch Backing Plate (OEM #35570-50 (Sonnax)) — For those seeking a more robust repair, aftermarket companies like Sonnax offer a billet steel backing plate that is twice as thick as the OE plate to prevent the flexing that causes the failure. This is an upgrade, not part of the standard OEM kit.
  Trusted brands: Sonnax
  Aftermarket price range: $50-$100

Related Codes That Often Appear With This One

• P1DA8-00 — Incorrect Gear Ratio Clutch A, B, or D Defective. This code is specifically mentioned in TSB 21-009-25 and points directly to the same internal clutch failure.
• P1D92-00 — Incorrect Gear Ratio - Clutch 4 Defective. Also listed in TSB 21-009-25, further confirming the diagnosis of the 'D' clutch assembly failure.
• P0700 — Transmission Control System Malfunction. This is a generic code indicating the TCM has stored a fault. It almost always appears with more specific transmission codes like P0733.

Technical Service Bulletins (TSBs) & Recalls

• 21-009-25 (Revisions A, B, C): Outlines the primary issue with the 'D' clutch, lists associated codes (P0733, P1DA8, P1D92), and provides the repair procedure for a wide range of Stellantis vehicles, including the Chrysler 300.
• 9100390 Rev 1: Reinforces that a 'D Clutch Repair Kit' is the correct fix and that transmission replacement is not required for P0733.
• S2621000003 REV.A: Groups P0733 with other codes for various 8-speed transmissions, indicating a known family of issues and recommends the D-clutch TSB as the first step.
• 21-039-24 (Multiple Revisions): A comprehensive bulletin that supersedes others, detailing the D clutch replacement procedure and listing all affected vehicles.

Platform-Specific Known Issues

• Chrysler has issued multiple revisions of TSB 21-009-25 for the 8-speed transmission family (including the 850RE in the 300), specifically citing P0733 and outlining a repair for the 'D' clutch assembly.
• TSB #9100390 Rev 1 explicitly warns dealers that a full transmission replacement is NOT required for this code and that performing one may be subject to chargeback, reinforcing that the clutch kit is the correct repair.
• The TSB specifies that this issue typically applies to vehicles with at least 7,000 miles (11,265 km).
• The official labor time for the D-clutch replacement on the Chrysler 300 (LX platform) is 6.7 hours.

Mechanic-Grade Diagnostic Values

• Transmission Solenoid Resistance — expected: 5.0 ohms at 68°F (20°C). Failure: A reading significantly higher or lower than 5.0 ohms indicates a faulty solenoid.
• D-Clutch Air Pressure Test — expected: The clutch pack should engage with an audible 'thud' and hold pressure with no significant audible leaks when shop air (approx. 75 PSI) is applied to the D-clutch circuit port on the case after valve body removal.. Failure: A hissing sound indicating a leak, or failure of the clutch pack to actuate, confirms an internal seal failure within the D-clutch assembly.
• Clutch Volume Index (CVI) for OD Clutch (used in 2-3 shift) — expected: A value between 48 and 150 is typical for a healthy OD clutch in a related Chrysler transmission.. Failure: A CVI value outside of the expected range indicates excessive wear or a hydraulic leak in the clutch circuit, prompting the TCM to log a fault.

Scan Tool Commands That Help

• wiTECH (Chrysler Dealer Tool): Quick Learn — This procedure must be performed after replacing the D-clutch, valve body, or entire transmission. It resets and relearns the clutch adaptive values. The transmission fluid must be at least 55°C (131°F) to initiate the procedure.
• wiTECH (Chrysler Dealer Tool): Reset Adaptive Values — This function is selected under the 'Misc Functions' tab for the TCM and is performed immediately before running the 'Quick Learn' procedure to clear old data.
• wiTECH (Chrysler Dealer Tool): Clutch Air Pressure Tests (Service Info) — This is not a direct command, but the detailed procedure referenced in TSB Z21 FSAR-TSB-4302 for definitively diagnosing the D-clutch leak after the valve body is removed.
• wiTECH (Chrysler Dealer Tool): Adaptation Drive Learn Procedure — An alternative, more involved procedure for relearning shift adapts if 'Quick Learn' is unavailable or does not resolve shift quality issues. It involves driving the vehicle under specific temperature and load conditions.

Wiring & Ground Locations

• Transmission Control Module (TCM) — Under the driver's side dashboard, located at the bottom of the steering column behind the knee panel.. While unlikely to be the cause, knowing the TCM location is critical for diagnosing communication issues or checking its connections if all mechanical and sensor checks pass.
• TCM Fuses (Engine Bay) — In the front fuse box (under the hood, passenger side). Specifically, fuses F05 and F37 have been identified as related to the TCM in similar models.. Loss of power to the TCM can cause various transmission codes and malfunctions. Checking these fuses is a basic but essential electrical diagnostic step.
• TCM Fuse (Trunk) — In the rear fuse box located in the trunk, behind the battery. Fuse F26 may be related to the transmission module in some configurations.. Similar to the engine bay fuses, this is a potential power source for the TCM that should be verified during electrical diagnosis.
• Transmission Main Connector — On the transmission case itself. The valve body must be dropped to release a metal bracket holding the main connector to the TCM (Mechatronic unit).. This connector is the primary interface for all sensors and solenoids. It is disconnected during the TSB repair and must be reseated correctly. Any damage to the pins or seals here could cause a variety of transmission faults.