2019 Subaru Ascent Transmission Control Module and CVT Failures

Known Issues, Recalls, and TSBs for the 2019 Subaru Ascent Transmission

The 2019 Subaru Ascent, particularly in its first model year, is known for significant issues related to its TR690 CVT. These problems are so widespread that they have led to multiple recalls, technical service bulletins (TSBs), a warranty extension, and a class-action lawsuit. Many of these issues are directly linked to the Transmission Control Module (TCM) and its programming.

Recall WUV-07 and the Successor, WRK-21

Initially, Subaru issued recall WUV-07 for over 76,000 2019 Ascent vehicles. The recall addressed an issue where a transmission hydraulic sensor could incorrectly measure fluid pressure, causing the TCM to reduce pressure. This could lead to the CVT's drive chain slipping, potentially causing a loss of power. The fix involved reprogramming the TCM and, in some cases, replacing the sensor harness or the entire transmission if chain slip was detected.

This was later superseded by a more comprehensive recall, WRK-21 (NHTSA ID: 21V-955), which covered nearly 200,000 Subaru vehicles, including the 2019-2020 Ascent. This campaign again pointed to an improper program in the TCM that could allow the clutch to engage before the drive chain was fully clamped, leading to slippage, damage to the chain guide, and eventual chain breakage. A broken chain results in a complete loss of power, increasing the risk of a crash. The remedy for WRK-21 involves reprogramming the TCM, inspecting historical data for chain slip, and performing a videoscope inspection of the chain guide. 🎬 Watch: How the WRK-21 recall fix can sometimes cause issues If any damage or significant slip history is found, the entire transmission assembly is replaced at no cost to the customer.

Subaru CVT Warranty Extension

Due to the widespread issues, Subaru extended the powertrain warranty for the CVT on affected vehicles. For vehicles that have the WRK-21 recall performed but do not receive a new transmission, the warranty on the CVT for chain-slip-related failures is extended to 10 years or 100,000 miles, whichever comes first. This covers a one-time replacement of the CVT assembly if it fails due to chain slip.

Symptoms of a Failing Transmission Control Module

A failing TCM or a related transmission problem in the 2019 Ascent can manifest in several ways. Because the TCM is central to the transmission's operation, symptoms are often severe and should not be ignored.

• Hesitation, Jerking, or Shuddering: The vehicle may hesitate or lurch during acceleration. A shudder or vibration, especially during low-speed acceleration, is a common complaint.
• Warning Lights: The Check Engine light, AT OIL TEMP light, or other malfunction indicators may illuminate on the dashboard.
• Loss of Power: In severe cases, the vehicle may suddenly lose all motive power while driving, a primary safety concern addressed by the recalls.
• Stalling: The engine may stall, particularly at low speeds or when coming to a stop.
• Erratic Shifting and Noises: You might hear a high-pitched whine, a sound like a belt slipping, or notice the engine RPMs changing unexpectedly without a corresponding change in speed.

Common OBD-II Diagnostic Codes

If the Check Engine Light is on, a scan tool may reveal specific trouble codes. While any P07xx code indicates a transmission-related fault, codes like P0700 (Transmission Control System Malfunction) and P0613 (TCM Processor) point directly toward the control system. Other codes may relate to incorrect gear ratios or sensor failures.

Programming and Installation: A Dealer-Level Task

The TCM must be programmed to the vehicle's specific Vehicle Identification Number (VIN). This process pairs the module to the rest of the car's electronics. Without proper programming, the vehicle will not start or run correctly. The TCM is typically located on the transmission's valve body, and they are often replaced as a single assembly.

This programming requires specialized equipment and software, specifically the Subaru Select Monitor (SSM) tool. While some high-end independent shops with J2534 pass-through devices may be able to perform this programming, it is most reliably done by a Subaru dealership. This is not a DIY-friendly job due to the software requirements. After installation and programming, a relearn procedure may also be necessary to calibrate 🎬 Watch: How to perform a Subaru TCM update and quick-learn the transmission's shift points and pressures.

Buying a Used 2019 Ascent Transmission Control Module

Given the high cost of a new transmission, a used TCM and valve body assembly can be a cost-effective option. However, due to the specific issues with this model, extreme care must be taken.

• Verify the Part Number: The most critical step is to match the OEM part number exactly. The part numbers for the 2019 Ascent TCM have been superseded multiple times (e.g., 30919AF98A, 30919AF98B, etc., up to 30919AF98G). Always purchase the latest version available or the exact number from your original part.
• Buy the Assembly: It is highly recommended to purchase the TCM and valve body as a complete, tested unit. Since they are integrated, separating them can introduce problems.
• Physical Inspection: Before purchasing, inspect the unit for any signs of physical damage, especially to the electrical connectors. Ensure there is no corrosion or bent pins.
• Factor in Programming Costs: Remember that the purchase price is not the final cost. You must budget for professional programming by a dealer or a qualified specialist, which can add several hundred dollars to the total repair cost.
• Source is Important: Purchase from a reputable recycler that offers a warranty. Given the high failure rate of the TR690 transmission, you want protection against receiving a part from a vehicle that had the same underlying issues.

Replacement Cost Comparison

The cost to address a TCM or transmission issue can vary widely depending on the ultimate diagnosis. Always have the vehicle diagnosed and check for open recalls before spending money on parts.

Frequently Asked Questions