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2020 Ascent Transmission Shudder/Jerking at Low Speeds

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Mike T. · rep 0 · May 25, 2:19 AM · 1 replies · solved · Question

Vehicle: 2020 Subaru Ascent Limited

Hello everyone, I'm hoping someone can shed some light on an issue I'm having with my 2020 Subaru Ascent Limited, which has about 45,000 miles on it. Lately, I've noticed a distinct shudder or jerking sensation, especially when accelerating from a stop or at very low speeds (under 20 mph). It feels like the car is struggling to find the right gear or the torque converter isn't engaging smoothly.

It seems to be more noticeable when the engine is cold or after the car has been sitting for a while. Once I'm up to speed, it drives fine, but those initial accelerations are really concerning. It's not a constant thing, but it happens frequently enough to be annoying and make me worried about the transmission's longevity.

Has anyone else with a 2020 Ascent experienced this? Could this be related to the CVT or torque converter? Are there any TSBs or recalls I should be aware of for this specific problem?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:19 AM

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ClearTheCode admin answer:

The shuddering and jerking you're describing in your 2020 Subaru Ascent, particularly at low speeds or during initial acceleration, is a recognized concern for some Ascent owners and points directly to potential issues within the Continuously Variable Transmission (CVT) or its torque converter. The Ascent's heavier weight and the demands placed on its CVT can sometimes exacerbate these issues.

Here's a detailed look:

  1. Commonality: This is a known issue, and Subaru has addressed similar complaints in the Ascent. The symptoms often align with torque converter clutch engagement problems.
  2. Diagnostic Focus:
    • Torque Converter: The torque converter is a strong suspect. If it's not engaging or disengaging smoothly, it can cause the shudder or hesitation you feel.
    • CVT Fluid Condition: While less likely to be the primary cause of a shudder in a newer vehicle, degraded or incorrect CVT fluid can contribute to poor performance.
    • Transmission Control Module (TCM) Software: Software calibration issues can sometimes lead to rough engagement.
  3. Relevant TSBs/Recalls: Subaru has issued several TSBs related to the Ascent's CVT and torque converter.
    • TSB 16-121-19R (and subsequent revisions): This TSB specifically addresses torque converter shudder and other drivability issues for certain Ascent models. It often involves a software update and, if the problem persists, torque converter replacement. It's crucial to have a dealership check for all applicable TSBs for your VIN.
    • Recall WRL-21 (NHTSA 21V-777): While this recall was for a different issue (CVT chain slip detection logic), it highlights Subaru's ongoing efforts to refine the Ascent's transmission.
  4. OBD Codes: While a check engine light might not be on, a pending code like P0700 (Transmission Control System Malfunction) or specific torque converter clutch codes (e.g., P2764 - Torque Converter Clutch Pressure Control Solenoid Control Circuit Low) could be present.

When to See a Shop: You should take your 2020 Ascent to a Subaru dealership immediately. This is a significant drivability concern that could worsen if left unaddressed.

  • Request that they specifically check for TSB 16-121-19R and any other relevant transmission-related service bulletins for your VIN.
  • They will perform a comprehensive diagnostic scan, check CVT fluid, and likely perform a specific test drive to replicate the shudder.
  • The repair could involve a TCM software update, a torque converter replacement, or in some cases, a full CVT replacement. Given the model year and mileage, this repair may still be covered under Subaru's powertrain warranty or an extended service program related to these known issues.
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