P0604 on 2022-2026 Dodge Durango: Internal RAM Error Causes and Fixes

What's Unique About the 2022-2026 Dodge DURANGO

For this specific generation of Durango and its platform mates (like the Jeep Grand Cherokee and Ram 1500), Dodge/Stellantis has issued Technical Service Bulletin (TSB) 18-044-26 that groups P0604 with other internal processor codes. This strongly suggests the root cause is often a software glitch that can be fixed with a dealer-installed update, rather than an immediate hardware failure requiring a costly PCM replacement. This is a common pattern seen in other modern Ram/Dodge/Jeep vehicles where software updates are the first and most frequent solution for this code.

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
• Engine may stall, run rough, or hesitate, sometimes dying while driving and then restarting.
• Vehicle may not start (cranks but does not fire)
• Harsh or erratic transmission shifting
• Other warning lights, like the ABS or Traction Control light, may illuminate
• Vehicle may enter a reduced-power "limp mode"
• Failed emissions test due to OBD-II monitor readiness issues

Most Likely Causes

1. PCM Software Requires Update 🔴 High Probability Manufacturer TSB #18-044-26 directly addresses this code as being potentially resolved by a software reflash, indicating a known software bug in the original programming for this platform.
   How to confirm: A Dodge dealership or a shop with a subscription to OEM service information (like a wiTECH scan tool) can check the vehicle's VIN to see if the TSB applies and if a software update is available by comparing the current calibration ID to the latest version.
   Typical fix: Perform a PCM software update (reflash) using dealer-level diagnostic tools. This service typically costs between $100 and $250.
   Est. part cost: $0
2. Low Battery Voltage or Poor Connections 🟡 Medium Probability → Shop Vehicle Battery Modern control modules are highly sensitive to voltage fluctuations. A weak battery or poor ground connection can cause a voltage drop during startup, corrupting the PCM's RAM self-test and falsely triggering a P0604 code.
   How to confirm: Test the battery voltage at rest (should be >12.4V) and while cranking (should stay >9.6 🎬 Watch: How to perform a battery test using a multimeter.V). Inspect all battery terminals, chassis grounds (e.g., G104, G105 on similar platforms), and PCM power/ground connections for corrosion or looseness. A voltage drop test at the PCM connector can confirm high resistance in the circuit.
   Typical fix: Clean battery terminals and ground points, or replace a weak or failing battery. Ensure all connections are tight and free of corrosion.
   Est. part cost: $150-$350
3. Failing Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM) If a software update does not resolve the code, and power/ground issues are ruled out, the hardware itself is faulty. This is the default conclusion after all other possibilities are exhausted.
   How to confirm: The code returns immediately after a successful software reflash, or a scan tool's specific RAM integrity test fails. A technician may also perform a bench test on the module.
   Typical fix: Replace the Powertrain Control Module. The new module must be programmed to the vehicle's VIN and configuration.
   Est. part cost: $800-$1500

Rare But Worth Checking

• Corrupted Aftermarket Tune: If the vehicle's PCM has been reprogrammed with a non-factory performance tune (e.g., via HP Tuners), a bad flash or incompatible software can corrupt the RAM and trigger a P0604 code. Returning the PCM to the stock tune is a critical diagnostic step.
• Failing Alternator: → Shop Alternator An alternator producing excessive AC ripple voltage or unstable DC voltage can disrupt the PCM's sensitive electronics, leading to memory corruption. The charging system should provide a stable voltage between 13.5V and 14.8V when the engine is running.

Diagnosis Steps

1. Scan the vehicle for all stored trouble codes. Note if P0604 is accompanied by P062B or P060C, as this strongly suggests a software issue per TSB 18-044-26. [NHTSA]
2. Check for applicable Technical Service Bulletins (TSBs) using the vehicle's VIN. For this vehicle, TSB #18-044-26 is the primary document of interest.
3. Thoroughly test the battery and charging system. Ensure battery voltage is stable and above 12.4V at rest and does not drop below 9.6V during cranking. Check that the alternator output is stable and within specification (typically 13.5V-14.8V).
4. Inspect all power and ground connections at the battery, chassis, and PCM for tightness and corrosion. Key ground points are often located on the engine block and inner fenders.
🎬 See this guide on how to check vehicle ground connections.
5. If an aftermarket tune is installed, flash the PCM back to the stock factory programming before proceeding.
6. If power, grounds, and tune are good, the next step is to follow the TSB recommendation and have a dealership or qualified shop perform a PCM software update.
7. If the code returns immediately after the software update, the PCM is highly suspect. 🎬 Watch this walkthrough on diagnosing and fixing the P0604 code. Advanced diagnostics, such as a RAM integrity test with an OEM scan tool or a module bench test, can confirm the failure.
8. Confirm PCM failure before replacement. The replacement PCM will require programming to the vehicle's VIN.

Parts You'll Likely Need

• Powertrain Control Module (PCM) Software Update — This is not a physical part, but a service. It is the most common and manufacturer-recommended first step for a P0604 code on this vehicle, as confirmed by TSB #18-044-26.
  Trusted brands: Mopar (via dealership service)
  OEM price range: $150-$275
  Aftermarket price range: N/A
• Powertrain Control Module (PCM) (OEM #68434931AA, 68434934AB (Varies by engine/year)) — If a software update and power supply checks do not resolve the issue, the PCM hardware itself has likely failed and requires replacement. Part numbers are highly specific to VIN, engine, and calibration.
  Trusted brands: Mopar (New or Remanufactured), Flagship One (Pre-programmed), SIA Electronics (Repair Service)
  OEM price range: $800-$1500
  Aftermarket price range: $500-$1000
• Battery — A weak or failing battery is a common cause of low voltage conditions that can trigger a P0604 code during startup.
  Trusted brands: Mopar, Interstate, DieHard
  OEM price range: $250-$400
  Aftermarket price range: $150-$300

Related Codes That Often Appear With This One

• P062B-00 — This code for 'Internal Control Module Fuel Injector Control Performance' is listed in the same TSB (#18-044-26) as P0604, pointing to a common software issue that is fixed with the same reflash. [NHTSA]
• P060C-00 — This code for 'Internal Control Module Main Processor Performance' is also listed in TSB #18-044-26, indicating a related internal PCM fault that is often fixed with the same software update. [NHTSA, 13]
• P0602 — This code for 'Control Module Programming Error' can appear alongside P0604, especially after a failed software update or if the module's memory is corrupted.

Technical Service Bulletins (TSBs) & Recalls

• 18-044-26: Addresses P0604-00, P062B-00, and P060C-00, which may be set in Active or Stored status, and can often be resolved with a PCM software update. This is the most critical TSB for this issue.

Platform-Specific Known Issues

• A known software issue documented in TSB #18-044-26 can cause this code to set, along with P062B and P060C. The prescribed fix is a PCM reflash.
• Like its platform mates (Jeep Grand Cherokee, Ram 1500), the Durango is highly sensitive to battery voltage, and a weak battery is a frequent trigger for this memory code.

Mechanic-Grade Diagnostic Values

• PCM Ground Circuit Resistance — expected: < 0.1 Ω. Failure: Resistance greater than 0.1 Ω indicates a poor ground connection which can cause voltage anomalies and trigger the P0604 code.
• Voltage at PCM Connector During Cranking — expected: > 9.6 V. Failure: Voltage dropping below 9.6V (or 9.0V in some sources) during engine crank can corrupt the PCM's self-test and trigger a false RAM error.
• Charging System Voltage (Engine Running) — expected: 13.5 V - 14.8 V. Failure: Voltage that is unstable, too low, or too high can cause electrical noise and memory corruption within the PCM.

Scan Tool Commands That Help

• wiTECH 2.0: Restore Vehicle Configuration — This function is used after installing a new or used PCM to align the module's configuration with the vehicle's factory-installed options.
• wiTECH 2.0: Learn ETC (Electronic Throttle Control) — After a PCM replacement or reflash, this procedure is required to relearn the throttle body's idle and full-range positions.
• wiTECH 2.0: Check PCM Odometer / Write VIN — When installing a new (blank) or used PCM, the vehicle's correct VIN and mileage must be manually written to the module for it to function correctly with other vehicle systems like the instrument cluster and immobilizer.

Wiring & Ground Locations

• G904 / G905 — On similar but slightly older Durango platforms, these grounds are located on the lower left side of the engine.. These are primary engine grounds. High resistance at these points can cause system-wide voltage instability, a known trigger for code P0604.
• PCM Connector C2, Pins 4 & 6 — On the main PCM connector of similar Ram truck platforms.. These specific pins are documented as primary ground circuits for the PCM. A voltage drop test or resistance check directly at these pins can definitively rule out a bad ground connection to the module itself.
• Main Engine-to-Chassis Ground Strap — Typically a large braided strap running from the engine block to the firewall or frame rail.. A corroded or loose main ground is a common cause of intermittent and hard-to-diagnose electrical issues, including memory errors in sensitive modules like the PCM.

Real Owner Repair Stories

• Reddit user on r/MechanicAdvice (2010 Truck (similar P0604 issue)) — Persistent P0604 code that returns immediately after clearing, even without starting the engine.
  ❌ Tried (didn't work) Replacing the ECM with a programmed used unit., Performing a full load test on power and ground circuits to the ECM (all tested good)., Testing the battery and charging system (all tested good)., Completely disconnecting an aftermarket stereo system., Disconnecting an auxiliary battery.
  ✅ What actually fixed it The user had to get a second replacement ECM, as the first one was also faulty and produced the P0604 code immediately upon installation. This highlights that replacement modules can be defective.

When the Usual Fixes Don't Work

• While the most common fixes are a software update or battery/ground check, there are documented cases where these steps do not resolve the issue. In one instance, a technician replaced a PCM, which fixed other codes but introduced a persistent P0604. Despite verifying all power and ground circuits were good and removing all aftermarket electronics, the code remained. The problem was only solved after replacing the PCM a second time, indicating the first replacement module was faulty. This serves as a critical reminder that even new or remanufactured parts can be defective, and P0604 can sometimes point to a faulty replacement part rather than an underlying vehicle issue.

OEM Part Supersession History

• 68434931AA → 68434931AB, then 68434931AC — Standard part revision and software updates.
  Heads up: Part number 68434931AC is specified for the 2022-2023 Dodge Durango with the 3.6L engine, while the previous 'AA' version was for 2020-2021 models. Using the wrong hardware revision can lead to programming failures or operational issues.

Model Year Variations Within This Range

• 2022-2023 vs 2020-2021: The OEM part number for the Powertrain Control Module (PCM) for the 3.6L engine changed. The 2020-2021 models used part number 68434931AA, which was later superseded for 2022-2023 models by part number 68434931AC.