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

What's Unique About the 2012-2019 Chrysler 300

The 2012-2019 Chrysler 300 uses several versions of the ZF 8-speed automatic transmission (like the 845RE, 8HP45, and 8HP70). While generally reliable, they are sensitive to fluid condition and level. Chrysler has issued a Technical Service Bulletin (TSB) that specifically addresses P0733, grouping it with other codes and pointing towards potential internal clutch or valve body issues, rather than just simple sensor failures. This suggests a known pattern of wear or failure that the manufacturer has documented. The specific clutch pack used for 3rd gear (the 'E' clutch) is a known common failure point on this transmission family.

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 during shifts
• Harsh or jerky shifting, especially into 3rd gear
• Vehicle enters 'limp mode' (gets stuck in one gear, often 2nd)
• Failure to shift into or out of 3rd gear
• Reduced fuel economy
• Engine RPMs are higher than usual for a given speed

Most Likely Causes

1. Low or Dirty Transmission Fluid 🔴 High Probability The 8-speed transmission is a sealed unit without a dipstick, making fluid level checks difficult for DIYers. Fluid breaks down over time, losing its hydraulic properties and causing shifting issues.
   How to confirm: A technician must check the fluid level and condition using the fill plug on the transmission, often with the vehicle at a specific temperature (e.g., 122°F/50°C). The fluid should be clear red/brown and not smell burnt or contain excessive metal particles.
   Typical fix: Perform a transmission fluid and filter service. 🎬 Watch: Step-by-step guide to replacing the ZF 8-speed fluid and filter. This involves draining the old fluid, replacing the filter (which is often integrated into the transmission pan), and refilling with the correct specification fluid.
   Est. part cost: $150-$300 for a pan/filter kit and fluid
2. Faulty Valve Body or Shift Solenoids 🟡 Medium Probability Solenoids control the flow of fluid to engage clutches. Debris in the fluid can cause them to stick or fail. The manufacturer TSB points to valve body replacement as a potential fix if other steps fail.
   How to confirm: A professional scan tool can command individual solenoids to check their operation. Pressure testing the transmission can also reveal issues within the valve body. Solenoids can be tested for resistance (should be ~5.0-5.5 ohms) and for mechanical seal integrity with a vacuum tester (should hold over 20 in-Hg).
   Typical fix: Replacement of the transmission valve body 🎬 Watch: How to replace the TCM and valve body assembly. or the specific solenoid pack. This is an internal transmission repair.
   Est. part cost: $500-$1200 for a new or remanufactured valve body
3. Internal Transmission Failure (e.g., Worn Clutch Pack) ⚪ Low Probability The 'E' clutch pack, which is used to engage 3rd gear, is a known common failure point in the ZF 8-speed family, leading to slippage. Severe wear results in the TCM being unable to achieve the correct gear ratio.
   How to confirm: This is usually diagnosed after all other possibilities (fluid, solenoids, electronics) have been ruled out. Finding metal debris in the transmission pan is a strong indicator. A technician can also read the Clutch Volume Index (CVI) values with a scan tool; a high CVI for the applying clutch indicates it is worn out.
   Typical fix: Rebuilding or replacing the entire transmission assembly.
   Est. part cost: $2500-$5000+ for a rebuilt or new transmission
4. TCM Software Issue ⚪ Low Probability Manufacturers sometimes release software updates to correct shifting logic or compensate for normal wear.
   How to confirm: A dealership or properly equipped independent shop can check the current TCM software version against the latest available version from Chrysler using a tool like wiTECH.
   Typical fix: Flashing or reprogramming the Transmission Control Module (TCM) with the latest software.
   Est. part cost: $0-$200 (typically a labor charge)

Rare But Worth Checking

• Faulty Input/Output Speed Sensor: While a possible cause for this code in general, it's less common on this platform than fluid or internal issues. A failing sensor will typically set its own specific trouble code (e.g., P0722).
• Wiring Harness Damage: The wiring connecting the TCM to the transmission's internal components can become damaged, leading to erratic signals. This should be inspected if other tests are inconclusive. The main connector at the transmission case is a known area for fluid leaks which can damage pins.

Diagnosis Steps

1. Verify the transmission fluid level and condition. This is the most critical first step.
2. Use a professional scan tool (like wiTECH) to check for any other stored transmission codes and to view live data, specifically the Clutch Volume Index (CVI) values for the clutch packs.
3. Inspect the transmission wiring harness and the main electrical connector for any visible damage, corrosion, or fluid intrusion.
4. If fluid is old or dirty, perform a complete transmission fluid and filter service using the OEM-specified fluid (e.g., Mopar ZF 8&9 Speed ATF).
5. If the problem persists, follow the diagnostic procedures outlined in Chrysler's TSB S2621000003 REV. A, which may involve testing the valve body and internal clutches.
6. Test shift solenoids for correct resistance (~5.0-5.5 ohms) and vacuum holding capacity (>20 in-Hg).
7. If a valve body issue is suspected, it should be tested and replaced if found to be faulty. After replacement, a 'Transmission Quick Learn' or adaptation reset procedure must be performed.
8. If all other components test good, an internal transmission inspection for worn clutch packs (specifically the 'E' clutch) or other mechanical damage is necessary.

Parts You'll Likely Need

• Transmission Pan and Filter Kit — The filter is integrated into the pan on the ZF 8-speed transmission. A fluid service requires replacing the entire pan assembly.
  Trusted brands: Mopar, ZF
  OEM price range: $150-$250
  Aftermarket price range: $100-$200
• Automatic Transmission Fluid (OEM #68218925AB (Mopar ZF 8&9 Speed ATF)) — This is the required fluid for any service. Using the wrong fluid can cause severe damage.
  Trusted brands: Mopar, Liqui Moly, Pentosin
  OEM price range: $25-$35 per liter
  Aftermarket price range: $15-$25 per liter
• Transmission Valve Body — A common failure point that causes pressure regulation issues, leading to slipping and incorrect ratio codes. The TSB specifically mentions this as a repair path.
  Trusted brands: Mopar, ZF
  OEM price range: $1000-$1500
  Aftermarket price range: $700-$1200 (remanufactured)

Related Codes That Often Appear With This One

• P0716 — Input/Turbine Speed Sensor Circuit Range/Performance. This code often appears with P0733 as the TCM uses this sensor's data to detect the gear ratio problem.
• P1B13 / P1B14 — These manufacturer-specific codes are listed in the same TSB as P0733 for the 8-speed transmissions, indicating they can stem from a common root cause within the transmission.

Technical Service Bulletins (TSBs) & Recalls

• S2621000003 REV. A: Groups P0733 with other codes for 8-speed transmissions and provides diagnostic guidance, suggesting potential clutch or valve body issues.

Platform-Specific Known Issues

• Chrysler TSB S2621000003 REV. A directly addresses P0733 on 2012-2023 Chrysler 300 models with 8-speed transmissions. It groups this code with several others and provides a diagnostic path that may lead to clutch repair or valve body replacement, indicating a known issue beyond simple fluid problems.

Mechanic-Grade Diagnostic Values

• Shift Solenoid Resistance (VFS type) — expected: Approximately 5.0 to 5.5 Ohms at 68°F (20°C).. Failure: A reading significantly outside this range indicates a faulty solenoid coil.
• Shift Solenoid Mechanical Seal (Vacuum Test) — expected: Solenoid should hold a vacuum of 20 in-Hg or more.. Failure: A reading below 20 in-Hg indicates an internal leak in the solenoid, requiring replacement.
• Clutch Volume Index (CVI) — expected: Within the manufacturer's specified range for the given clutch (viewable on a scan tool).. Failure: A CVI value above the specified range indicates a worn clutch pack. A value below the range indicates binding. A value of zero indicates a large hydraulic leak in that circuit.

Hidden / Shadow Codes Worth Checking

• Clutch Volume Index (CVI) Data: Not a trouble code, but a set of manufacturer-specific data points that measure the volume of fluid needed to apply each clutch pack. This data provides direct insight into the mechanical wear of internal clutches, which is the root cause of many ratio codes. (see via Accessible through the TCM data stream on a professional scan tool with Chrysler-specific software, such as wiTECH.)

Scan Tool Commands That Help

• wiTECH or equivalent professional scan tool: Transmission Quick Learn — This procedure is required after replacing the transmission, valve body, or TCM. It must also be performed if the adaptation memory cells are cleared. It resets and relearns the clutch adaptive values to ensure smooth shifting.
• wiTECH or equivalent professional scan tool: Clear TCM Adaptives — Used to reset the transmission's learned shift behavior to factory defaults. This can resolve shifting issues but will cause temporarily poor shift quality until a 'Quick Learn' or sufficient drive cycles are completed.

Wiring & Ground Locations

• Main Transmission Connector (8HP) — A large, round, bayonet-style connector on the passenger side of the transmission case.. This is the sole electrical interface for the internal mechatronics (TCM and solenoids). A poor connection, fluid intrusion from a failed seal, or a bad ground (Pin 14) can cause numerous transmission faults, including ratio codes.
• Engine Block / Bellhousing Grounds — Various ground straps and connection points exist between the engine/transmission assembly and the vehicle's chassis/K-member.. A poor engine-to-chassis ground can cause electrical noise and voltage issues for all engine and transmission electronics, potentially leading to erratic sensor readings and incorrect TCM calculations.

Real Owner Repair Stories

• Ram Heavy Duty Forum user (Ram with 8HP75-LCV transmission (same family as in the 300), 26,000 miles) — P0733 'Gear 3 Incorrect Ratio' code and 'Service Transmission' message on the dash.
  ❌ Tried (didn't work) The dealership initially diagnosed the issue as a faulty valve body, which is a common fix.
  ✅ What actually fixed it Upon warranty request from the manufacturer, the technician dropped the transmission pan and found metal shavings. This discovery changed the diagnosis from a valve body to a critical internal failure. The entire transmission assembly was replaced under warranty.

When the Usual Fixes Don't Work

• In one documented case involving a similar vehicle with the same transmission family, the initial diagnosis pointed to the valve body, a very common cause for P0733. However, further inspection revealed metal in the transmission pan, indicating a deeper mechanical failure of the clutch packs. This led to a full transmission replacement instead of just a valve body swap, highlighting that the common fix is not always the correct one and that inspecting for debris is a critical diagnostic step.

Model Year Variations Within This Range

• 2012-2019: The specific version of the 8-speed transmission varies by engine. V6 models typically use the 845RE (based on the ZF 8HP45), while V8 models use the heavier-duty ZF 8HP70. While they share a common architecture and fault patterns (like P0733), their torque limits and some internal components are different.
• 2012-2019: The TCM software has been updated multiple times via Technical Service Bulletins (TSBs) to address shift quality concerns. A vehicle may have outdated software that contributes to harsh shifting or incorrect adaptive learning, which could potentially lead to a ratio code.