P0733 on 2012-2019 Chrysler 300: Gear 3 Incorrect Ratio Causes and Fixes

What's Unique About the 2012-2019 Chrysler 300

The Chrysler 300 from this era uses the ZF-designed 8-speed automatic (845RE/8HP45/8HP70), which is known for this specific issue. While generic causes like low fluid are possible, this platform has a documented pattern of internal failures related to P0733. Chrysler has issued Technical Service Bulletins (TSBs) that point technicians toward specific clutch or valve body issues rather than simple sensor failures, acknowledging a known weakness. For this transmission family, the issue is often traced to the 'D' or 'E' clutch packs. This means a full transmission replacement is often not necessary if the correct, targeted repair is performed.

Symptoms You May Notice

• Check Engine Light is on
• Transmission slipping, hesitating, or flaring (engine RPMs rise without an increase in speed) when shifting into or driving in 3rd gear
• Harsh, jerky, or delayed shifts, especially on cold starts
• Vehicle enters "limp mode," getting stuck in a single gear (often 3rd or 4th)
• Failure to shift into or out of 3rd gear
• Poor or delayed acceleration
• A 'bang' or 'clunk' when shifting, particularly when cold

Most Likely Causes

1. Internal Clutch Pack Failure ('D' or 'E' Clutch) 🔴 High Probability A known weakness in this transmission family. Multiple TSBs (like 21-009-25) point to this failure. Some sources indicate a thin factory backing plate in the 'D' clutch pack can flex or break, causing uneven wear and eventual slippage. This issue is widely documented on platform-mate vehicles like the Ram 1500.
   How to confirm: Requires a transmission pressure test and likely disassembly by a professional to inspect the clutch pack for burned plates or a failed backing plate. An advanced scan tool may also show related codes like P1DA8 or P1D92, which are specifically mentioned in TSBs and point to this failure.
   Typical fix: Internal transmission repair to replace the specific failing clutch pack and any related damaged components. A 'D Clutch Repair Kit' (e.g., Mopar 68676887AB) is often used per the TSB. This is a job for a transmission specialist.
   Est. part cost: $200-$800 for clutch kits, seals, and upgraded parts from brands like Sonnax.
2. Failing Valve Body or Shift Solenoid 🟡 Medium Probability → Shop Transmission Valve Body The valve body (mechatronics unit) directs hydraulic fluid to engage the correct clutches. Debris from normal wear (or a failing clutch) can clog passages or cause solenoids to stick, preventing proper pressure for 3rd gear engagement. Aftermarket solutions like the Sonnax Zip Kit (ZF8-ZIP) exist specifically to address pressure losses in worn valve bodies.
   How to confirm: A technician will use a high-end scan tool to monitor solenoid commands vs. actual pressure and performance. A visual inspection of the valve body for debris is also common during a pan drop.
   Typical fix: Replacement of the faulty solenoid or the entire valve body assembly. In some cases, a valve body rebuild using a kit like the Sonnax Zip Kit can restore function.
   Est. part cost: $500-$1200 for a valve body assembly.
3. Low or Dirty Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly These transmissions are 'sealed for life' but are very sensitive to fluid level and quality. There is no dipstick for easy checking. A leak or fluid degradation over many miles can cause hydraulic pressure issues. Many owner forum posts for P0733 begin with a fluid and filter change, though it often doesn't solve the problem if mechanical damage is already present.
   How to confirm: The vehicle must be lifted level, and the fluid level checked via a fill plug at a specific temperature (between 30°C/86°F and 50°C/122°F), a process typically done by a shop. The fluid condition (dark, burnt smell, debris) is a key indicator.
   Typical fix: Perform a complete fluid and filter service using the correct Mopar 8&9 Speed ATF (Part #68218925AB) or equivalent ZF-Lifeguard 8 fluid (Part #S671090312). The filter is integrated into the transmission pan, which must be replaced as a unit (Mopar Part #68225344AA). If the fluid is very dirty, it may be a symptom of a larger internal problem.
   Est. part cost: $150-$300 for fluid and a pan/filter kit.

Rare But Worth Checking

• Faulty Transmission Speed Sensor: → Shop Transmission Assembly While possible, it's less common for this specific code on this platform compared to mechanical failures. Usually, a failing speed sensor will trigger its own specific circuit code, such as P0722.
• TCM Software Issue: A corrupted or outdated software calibration can cause the TCM to misinterpret sensor data. A dealer or qualified shop can check for available software updates. This is a good first step but is rarely the root cause for a persistent P0733.

Diagnosis Steps

1. Verify the code with a quality OBD-II scanner.
2. Check for any available Technical Service Bulletins (TSBs) for your vehicle's VIN. TSB 21-009-25 is highly relevant to this code on this platform.
3. Check the transmission fluid level and condition. This must be done by a professional as there is no dipstick and it requires a specific procedure with the vehicle level and at a certain temperature (86°F-122°F).
4. Inspect for any transmission fluid leaks. The fluid contains a dye visible under black light.
5. Use an advanced scan tool to monitor live data, including input/output speed sensor readings, commanded vs. actual gear, and clutch slip counters.
6. If fluid is full and clean, and TSBs point to an internal failure, the next step is often an air pressure test of the clutch circuits, which requires removing the valve body and using a special test plate.
7. If pressures are low or erratic for the 3rd gear circuit, the issue is likely an internal clutch pack, requiring transmission removal and disassembly for inspection and repair, as outlined in the TSB.

Parts You'll Likely Need

• Transmission Filter and Fluid Kit (OEM #Pan/Filter: 68225344AA, Fluid: 68218925AB) — The first step in addressing potential hydraulic issues. The filter is integrated into the pan. The correct fluid (Mopar 8&9 Speed ATF or ZF-Lifeguard 8) is critical.
  Trusted brands: Mopar, ZF, Mahle
  OEM price range: $200-$330 for pan and 6-8 quarts of fluid.
  Aftermarket price range: $150-$250
• D-Clutch Repair Kit (OEM #68676887AB or 68676892AA) — This is the specific kit called for by TSBs to fix the most common root cause: a burned-out internal clutch pack. This is a specialist part for a transmission rebuild.
  Trusted brands: Mopar
  OEM price range: $200-$400
  Aftermarket price range: N/A
• Valve Body Assembly — Often replaced to resolve hydraulic pressure and solenoid issues that cause slipping. May be contaminated by debris from a failing clutch.
  Trusted brands: Mopar, ZF
  OEM price range: $800-$1200
  Aftermarket price range: $500-$900

Related Codes That Often Appear With This One

• P0734 (Gear 4 Incorrect Ratio) — If multiple gear ratio codes appear, it strongly suggests a widespread hydraulic issue, such as a failing valve body, low fluid, or a clogged filter affecting multiple clutch circuits.
• P1DA8 (Incorrect Gear Ratio Clutch A, B, or D Defective) — This code is specifically mentioned in TSB 21-009-25 alongside P0733 and points directly to the internal 'D' clutch pack failure, strongly confirming the diagnosis.
• P0700 (Transmission Control System Malfunction) — This is a generic code indicating the TCM has stored a fault. It will almost always be present alongside a more specific code like P0733 and simply means 'check for other transmission codes.'

Technical Service Bulletins (TSBs) & Recalls

• TSB 21-009-25 (and its revisions): This is the most critical TSB. It specifically addresses DTC P0733 on 8-speed transmissions, acknowledges the 'D' clutch assembly failure, and provides a specific repair procedure using a kit instead of a full transmission replacement.
• TSB #9100534 / #9100390: Also noted for platform mates, these TSBs explicitly state that for DTC P0733, a specific repair is available and full transmission replacement is not required.

Platform-Specific Known Issues

• The 8HP/845RE family of transmissions has a documented history of issues with the 'D' and 'E' clutch packs, which are involved in the 3rd gear shift, sometimes leading to this specific code.
• Symptoms often appear or are most severe on a cold start, with the first 2-3 shift of the day being harsh or slipping.

Mechanic-Grade Diagnostic Values

• Shift Solenoid Resistance — expected: 5.0 ohms at 20°C (68°F). Failure: A reading significantly higher or lower than 5.0 ohms indicates a faulty solenoid coil.
• Clutch Fill Pressure / Time (Advanced Scan Tool) — expected: Values vary, but should be compared to a known-good vehicle. Negative pressures indicate a vacuum (good seal), while high positive pressures can indicate a leak. Fast fill times are desired.. Failure: Significantly high positive fill pressure (e.g., >150 mbar) or very long fill times (e.g., >40ms) for the D or E clutch can indicate internal seal leakage or a worn clutch pack.

Hidden / Shadow Codes Worth Checking

• P1D92: Incorrect Gear Ratio - Clutch 4 Defective. This is a Chrysler-specific code that is often set along with P0733 and is mentioned in the same TSBs. It more definitively points to an internal mechanical failure rather than a simple sensor or fluid issue. (see via Dealer-level scan tools like wiTECH or advanced aftermarket scanners such as AlfaOBD.)

Scan Tool Commands That Help

• wiTECH or AlfaOBD: Quick Learn / Reset Clutch Adaptation Values — This procedure is mandatory after replacing a valve body, transmission, or performing major internal repairs. It resets the learned values for clutch fill times and pressures. Failing to perform this can lead to harsh shifts, premature wear, and new codes being set.
• wiTECH or AlfaOBD: View Clutch Fill Times and Pressures — During diagnosis, monitoring these live data PIDs for each clutch (A-E) can help pinpoint which specific clutch circuit is leaking or slow to respond, narrowing down the internal fault before disassembly.

Wiring & Ground Locations

• Transmission Main Connector (to Mechatronics) — On the passenger side of the transmission case, where the main vehicle harness connects to the internal mechatronics unit (TCM/Valve Body).. A leak at the connector sleeve (a common issue) can allow transmission fluid to wick into the connector pins and harness, causing corrosion and disrupting communication between the vehicle and the TCM. This can lead to erratic shifting, false sensor readings, and various transmission codes, including ratio errors.
• TCM/PCM Ground — While the TCM is internal to the transmission, the Powertrain Control Module (PCM) which communicates with it is typically located in the engine bay. Its primary ground points are on the chassis or engine block.. Although unlikely to be the primary cause for a specific gear ratio code, a poor ground to the main PCM can cause a wide range of communication errors and unpredictable behavior from electronically controlled components like the transmission.

Real Owner Repair Stories

• JLwranglerforums.com user (2020 Jeep Wrangler (JL) with 3.6L and 8-speed auto) — Vehicle would not reverse, stuck in 2nd gear in Drive, Check Engine Light on.
  ❌ Tried (didn't work) Restarting the vehicle multiple times.
  ✅ What actually fixed it The dealer diagnosed an active P1D92 code. The repair was a replacement of the transmission valve body and a PCM software update.

OEM Part Supersession History

• 68676887AA → 68676887AB — This is the Mopar part number for the 'Output Shaft Kit', which is often used as the repair kit for the D-clutch failure. The change from AA to AB typically indicates a minor revision or change in manufacturing or included components.

Model Year Variations Within This Range

• 2012-2014: These earlier models primarily used the first-generation ZF8HP45 (Chrysler 845RE) and ZF8HP70 transmissions. These are the units most commonly associated with the TSBs for D-clutch failure.
• 2015-2019: Around 2015, Chrysler began phasing in the second-generation ZF8, designated 8HP50 and 8HP75 (Chrysler 850RE). While mechanically similar, they feature some internal updates and different valve body/solenoid arrangements. While still susceptible to similar failures, diagnostic procedures and parts like valve body kits (e.g., Sonnax ZF8-GEN2-ZIP) may be specific to the generation. It is critical to identify the exact transmission model before ordering parts.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Uconnect 8.4" Screen Delamination / Ghost Touch 🟠 Medium — Very common on 2017-2018 models, but can occur on others. Heat and humidity accelerate the failure of the screen adhesive, causing bubbles and phantom screen presses. (Ref: Multiple TSBs exist that guide dealers to replace the entire radio unit, as it is considered a hardware failure.)
• Rotary Dial Shifter Failure / Stuck in Park 🟠 Medium — Moderately common. Can be caused by internal electronic or mechanical failure in the shifter module, or issues with the brake-shift interlock. Can prevent the vehicle from starting or shifting out of Park. (Ref: NHTSA has investigated rollaway risks associated with these shifters, but individual failures are often diagnosed at the dealer level.)
• 3.6L Pentastar 'Tick' / Lifter & Rocker Arm Failure 🔴 High — A well-known issue on the 3.6L V6, particularly earlier models (pre-2016). A ticking noise from the cylinder head, especially on the left side, is the primary symptom. If ignored, it can lead to camshaft damage. (Ref: Chrysler extended the warranty for the left-side cylinder head on some model years to address this specific issue.)
• 5.7L HEMI 'Tick' / MDS Lifter Failure 🔴 High — Common on HEMI engines with the Multi-Displacement System (MDS). A roller on the lifter can seize, causing it to drag on and damage the camshaft. This often presents as a persistent ticking or tapping noise.
• Broken Park-Lock Lever (Lever Shifters) 🟡 Low — Extremely common on earlier second-gen models (pre-2015) with a traditional console shifter. A small pink plastic piece inside the shifter assembly breaks, preventing the car from shifting out of Park. (Ref: No TSB, but numerous DIY fixes and aftermarket metal replacement parts are available due to the high failure rate.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A complete, low-mileage used transmission assembly can be a cost-effective alternative to a dealership rebuild, especially if the labor costs for the internal repair are high in your area. If the price of a used unit from a reputable salvage yard is less than 50-60% of a full rebuild, it's worth considering.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the donor vehicle's VIN to confirm mileage and model year (to ensure compatibility).
• Ask for a warranty (typically 90 days or more from reputable sellers).
• If possible, inspect the fluid from the cooler lines. If it's dark black or smells burnt, walk away.
• Check the main electrical connector for any signs of fluid leakage or pin damage.

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

• D-Clutch Repair Kit (Mopar P/N 68676887AB) - This is the TSB-specified fix and using the OEM kit is the safest bet for the most common failure.
• Mechatronics/TCM - Due to programming and security (VIN lock), a used TCM is often not a viable plug-and-play option. A new or professionally remanufactured unit is required.

Aftermarket brands forum-validated for this vehicle:

• Sonnax (for valve body Zip Kits and other internal upgrades)
• ZF (as the original manufacturer of the transmission, their branded parts like pans and fluid are equivalent to OEM)

Brands owners have reported issues with on this vehicle:

• Unbranded, 'no-name' solenoid kits from online marketplaces. Solenoid quality and calibration are critical in the ZF8, and poorly made solenoids can cause more problems than they solve.

Real Owner Stories

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

Related OBD-II Codes

• P1DA8 — Specifically mentioned in TSBs as a related code that points to internal 'D' clutch pack failure.
• P1D92 — A companion code cited in technical bulletins that indicates internal transmission failure alongside P0733.
• P0734 — Related gear ratio error; owners often report symptoms progressing from 2-3 shift flares (P0733) to 3-4 flares (P0734) as internal clutch damage worsens.

Frequently Asked Questions