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2021 Ascent in Limp Mode - P0700 and P2764 Codes

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Nicole W. · rep 0 · May 22, 3:13 AM · 1 replies · solved · Question

Vehicle: 2021 Subaru Ascent Touring

Hey everyone,

My 2021 Subaru Ascent Touring just went into limp mode yesterday. The Check Engine Light, AT Oil Temp light, and Hill Start Assist lights are all on. When I scanned it, I got two codes: P0700 (Transmission Control System Malfunction) and P2764 (Torque Converter Clutch Pressure Control Solenoid Circuit Low).

The car feels very sluggish, almost like it's stuck in a high gear, and shifting is very rough. I'm worried about driving it like this. It has about 45,000 miles on it.

What do these codes typically indicate for the Ascent's CVT? Is this a common issue, and what's the likely repair? Is it safe to drive it a short distance to a dealership, or should I have it towed?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:13 AM

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ClearTheCode admin answer:

The P0700 and P2764 codes on your 2021 Subaru Ascent, especially when accompanied by limp mode and the AT Oil Temp light, strongly indicate a significant issue with the Continuously Variable Transmission (CVT). The P0700 is a generic code that tells you the Transmission Control Module (TCM) has detected a fault and has illuminated the CEL, while the P2764 is the specific code pointing to the problem.

Understanding the Codes:

  • P0700 (Transmission Control System Malfunction): This is an informational code from the engine's ECU, indicating that the TCM has stored a fault code. You need to read the TCM's specific codes to diagnose the problem, which you've done with P2764.
  • P2764 (Torque Converter Clutch Pressure Control Solenoid Circuit Low): This code specifically points to an electrical issue or malfunction with the torque converter clutch (TCC) pressure control solenoid. This solenoid is crucial for engaging and disengaging the torque converter clutch, which helps improve fuel efficiency and reduce heat. A 'circuit low' typically means there's an open circuit, a short to ground, or the solenoid itself has failed internally.

Common Causes for P2764 in Subaru CVTs:

  1. Faulty TCC Solenoid: The solenoid itself can fail electrically or mechanically, preventing proper operation of the torque converter clutch.
  2. Wiring Harness Issues: Damaged, corroded, or loose wiring/connectors leading to the TCC solenoid can cause a 'circuit low' condition.
  3. TCM Malfunction: Less common, but a faulty Transmission Control Module could be misinterpreting signals or failing to control the solenoid correctly.
  4. Internal Transmission Issue: In some cases, internal transmission wear or debris can affect solenoid operation, though the code usually points more directly to the solenoid or its circuit.

Likely Repair:

The most common repair for a P2764 code is the replacement of the Torque Converter Clutch Pressure Control Solenoid. This often requires dropping the transmission pan and accessing the valve body, which is an involved procedure.

Is it Safe to Drive?

No, it is not recommended to drive your Ascent with these codes and symptoms, especially in limp mode. Limp mode is designed to protect the transmission from further damage. Driving it could:

  • Cause further, more severe damage to the transmission components.
  • Lead to overheating of the transmission fluid (indicated by the AT Oil Temp light).
  • Result in a sudden loss of power or complete transmission failure, creating a dangerous situation.

When to See a Shop:

  • Immediately. You should have your vehicle towed to a Subaru dealership or a reputable transmission specialist. This is not a DIY fix for most owners.
  • The shop will perform a thorough diagnostic, including checking the solenoid's resistance, inspecting the wiring, and potentially dropping the transmission pan for a visual inspection of the valve body and fluid condition.

Given the vehicle's age and mileage, it's important to address this promptly to avoid more costly repairs.

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