P0746 on 2020-2021 Buick Encore: Pressure Control Solenoid 'A' Causes and Fixes

What's Unique About the 2020-2021 Buick ENCORE

The 2020-2021 model years are complex, as they include both the original Encore (with a 6-speed automatic) and the newer Encore GX. The P0746 code is particularly significant for the front-wheel-drive Encore GX models equipped with a Continuously Variable Transmission (CVT), specifically the GM VT40 (RPO MRG). On these specific vehicles, GM has identified a software issue that can cause a CVT pump priming delay, leading to this code and poor acceleration. Furthermore, TSB 21-NA-003 notes that on these VT40 CVTs, a sticking pressure regulator valve in the valve body can also cause P0746 and a loss of propulsion, sometimes intermittently.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2020-2021 model years include both the first-generation Buick Encore and the newer Buick Encore GX. The Encore uses a 1.4L engine with a 6-speed automatic transmission. The Encore GX offers 1.2L or 1.3L engines; front-wheel-drive (FWD) models use a CVT (GM VT40), while all-wheel-drive (AWD) models use a 9-speed automatic. The TSBs regarding software updates (A202301230) and internal valve body/pressure issues (21-NA-003) are specific to the Encore GX with the VT40 CVT.

Symptoms You May Notice

• Vehicle will not move when in Drive, Neutral, and/or Reverse.
• Reduced launch performance, especially during a quick exit from a stop/start event.
• Check Engine Light is on.
• Harsh, delayed, or erratic shifting.
• Transmission may feel like it's stuck in one gear (limp mode).
• Increased fuel consumption.
• Loss of propulsion while driving.

Most Likely Causes

1. Outdated Transmission Control Module (TCM) Software 🔴 High Probability → Shop Transmission Assembly Specific to CVT-equipped Encore GX models, a known software bug causes a pump priming delay after a stop/start event, as documented in TSB A202301230. This is the first and most common fix dealers will attempt.
   How to confirm: A GM dealer can verify if the vehicle's software is outdated and if TSB A202301230 applies to the VIN. This TSB is specifically for the Encore GX and its platform mate, the Chevy Trailblazer.
   Typical fix: Reprogramming the Transmission Control Module (TCM) with the updated software, followed by a Service Fast Learn (SFL) procedure.
   Est. part cost: $0 (if covered under warranty/service campaign)
2. Sticking Pressure Regulator Valve in Valve Body 🟡 Medium Probability → Shop Transmission Valve Body TSB 21-NA-003 specifically calls out that a sticking pressure regulator valve in the valve body of the VT40 CVT can cause P0746 along with other pressure-related codes and a loss of propulsion. This can be an intermittent condition.
   How to confirm: A technician would analyze scan tool freeze frame data to see if P0746 was the first code set, along with low primary/secondary pulley pressure readings. If the software update doesn't work, this is the next logical step.
   Typical fix: Replace the transmission valve body and pressure sensors. In some cases, only the solenoid body may need replacement if other specific solenoid codes are present.
   Est. part cost: $300-$600
3. Low or Contaminated Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly CVTs are sensitive to fluid level and condition. Low fluid can cause the pump to cavitate, leading to pressure faults. Contaminated fluid can cause valves and solenoids to stick.
   How to confirm: Check the transmission fluid level and condition according to the manufacturer's procedure. The fluid should be at the correct level, red in color, and free of debris or a burnt smell. The correct fluid is critical.
   Typical fix: Perform a transmission fluid drain and fill using the correct fluid, ACDelco CVT Fluid (GM Part #19260800 / 10-4092). If the fluid is low, the source of the leak must be identified and repaired.
   Est. part cost: $75-$200
4. Internal Transmission Failure (Chain/Pulley Damage) ⚪ Low Probability → Shop Transmission Assembly TSBs PIE0720A and 20-NA-120 link P0746 to a 'no-move' condition. TSB 20-NA-120 outlines a procedure to inspect the CVT chain and pulleys for damage with a borescope. If pressure issues from other faults are not addressed, the chain can slip and damage the pulleys, requiring a full transmission replacement. 🎬 Watch: A close-up look at the Encore GX CVT transmission.
   How to confirm: This requires extensive diagnosis by a transmission specialist, starting with a borescope inspection through the transmission filler cap to check for slip marks on the chain and pulleys. If damage is found, the transmission must be replaced.
   Typical fix: Replacement of the entire CVT assembly.
   Est. part cost: $4000-$7000+

Rare But Worth Checking

• Failed Pressure Control Solenoid 'A': → Shop Transmission Valve Body While the code directly names the solenoid, on this platform it is more often a symptom of a software or valve body issue. However, the solenoid itself can fail electrically or mechanically. 🎬 See this breakdown of how pressure control solenoids function and fail. It is typically replaced as part of the solenoid/valve body assembly.
• Wiring Harness Damage: Damage to the wiring between the TCM and the transmission can cause a loss of communication with the solenoid, triggering the code. A technician can test the circuit for continuity and shorts.
• Faulty Transmission Control Module (TCM): → Shop Transmission Assembly While rare, the TCM itself can fail, sending incorrect signals or no signal at all to the solenoid. This is usually diagnosed after all other possibilities (software, fluid, mechanical parts, wiring) have been eliminated.

Diagnosis Steps

1. Scan the TCM for all stored trouble codes. Note if P0746 appears with P0776 or other pressure codes mentioned in TSBs.
2. Check with a GM dealer to see if Service Update A202301230 (for CVT software) applies to your vehicle's VIN. This is the highest probability fix for the 'poor launch' symptom.
3. If symptoms match the software TSB, prioritize getting the TCM reprogrammed before any mechanical repairs.
4. Inspect the transmission fluid level and condition. The fluid must be clean, at the proper level (checked at 85-95°C), and be the correct type (ACDelco CVT Fluid).
5. If the software and fluid are good, a technician should consult TSB 21-NA-003 and analyze scan tool freeze frame data to check pulley pressure commands vs. actual pressures at the time of the fault.
6. Inspect the transmission wiring harness and connectors for any visible damage, corrosion, or loose connections.
7. If data points to a mechanical issue, the next step is replacing the valve body assembly as per TSB 21-NA-003.
8. As a final check before major repair, TSB 20-NA-120 recommends a borescope inspection of the CVT chain and pulleys for scoring or damage. If damage is present, the entire transmission must be replaced.

Parts You'll Likely Need

• CVT Fluid (OEM #10-4092 (GM #19260800)) — Required for any service. Using the correct fluid is critical for CVT operation. Low or contaminated fluid is a common cause of this code.
  Trusted brands: ACDelco
  OEM price range: $25-$40 per quart
  Aftermarket price range: $15-$25 per quart
• Automatic Transmission Control Valve Body (OEM #24288570 (Solenoid Body for 1.5L, check VIN)) — TSB 21-NA-003 identifies a sticking pressure regulator valve within the valve body as a primary cause of P0746 after software issues are ruled out. It often contains the solenoids.
  Trusted brands: ACDelco
  OEM price range: $250-$500
  Aftermarket price range: $200-$400
• Complete CVT Transmission Assembly — Required if a borescope inspection per TSB 20-NA-120 reveals damage to the CVT chain or pulleys, which can result from prolonged operation with incorrect hydraulic pressure.
  Trusted brands: ACDelco
  OEM price range: $4000-$7000+

Related Codes That Often Appear With This One

• P0776 — This code for 'Pressure Control Solenoid 'B' Performance' is explicitly mentioned alongside P0746 in TSB A202301230 related to the CVT software issue and TSB 21-NA-003 for internal pressure issues.
• P0747 — This code for 'Pressure Control Solenoid 'A' Stuck On' is mentioned with P0746 in TSBs PIE0720A and PIE0720 for severe 'no-move' conditions, indicating a related mechanical or hydraulic fault.
• P0700 — This is a generic code indicating the TCM has stored a fault. It acts as a general alert and will almost always appear with specific transmission codes like P0746.
• P0841, P0846, P0961, P0965 — These are various pressure sensor and solenoid performance codes that are listed together with P0746 in TSB 21-NA-003, pointing towards a valve body or internal hydraulic pressure problem in the VT40 CVT.

Technical Service Bulletins (TSBs) & Recalls

• A202301230: Addresses reduced launch performance and DTCs P0746/P0776 on CVT models due to a pump priming delay. Fix is a TCM software reprogram.
• PIE0720A / PIE0720: Engineering investigation into a 'no-move' condition where DTCs P0746 and P0747 are set.
• 21-NA-003: Details diagnosis for loss of propulsion with P0746 and other codes, pointing to a sticking pressure regulator valve in the valve body of the VT40 CVT.
• 20-NA-120: Provides instructions for inspecting the CVT chain and pulleys with a borescope for damage when pressure-related DTCs are present. If damage is found, the transmission must be replaced.

Platform-Specific Known Issues

• A known software issue in CVT-equipped models can cause a priming delay in the main pump after a stop/start event, leading to reduced launch performance and setting codes P0746 and P0776. This is addressed by a dealer-installed software update per TSB A202301230.
• A sticking pressure regulator valve inside the transmission valve body is a known mechanical fault on the VT40 CVT that causes loss of propulsion and sets P0746, as detailed in TSB 21-NA-003.
• Severe cases may result in the vehicle being unable to move in any gear, setting codes P0746 and P0747, as noted in TSBs PIE0720A and PIE0720. This may indicate a more serious internal transmission failure requiring further investigation or replacement.

Mechanic-Grade Diagnostic Values

• Line Pressure Commanded to Pulleys (in limp mode) — expected: 4000 kPa. Failure: When the TCM detects sticking valves, it commands a protective maximum pressure of 4000 kPa to both pulleys. Seeing this value on a scan tool like GDS2 confirms the TCM has entered this protective mode.
• Transmission Fluid Temperature for Service Fast Learn — expected: 70-100°C (158-212°F). Failure: The Service Fast Learn procedure will abort or fail to run if the transmission fluid temperature is outside this specific range.
• Pressure Control Solenoid Coil Resistance — expected: General range is 5 to 30 ohms. PWM solenoids are typically lower (around 5-10 ohms), while on/off solenoids are higher (around 20-30 ohms).. Failure: A reading of infinite resistance (OL) indicates an open circuit in the coil. A reading near zero ohms indicates a short circuit.

Scan Tool Commands That Help

• GDS2 (or equivalent professional scan tool): Service Fast Learn (SFL) — This procedure must be performed after replacing the valve body, solenoids, or the entire transmission, or after a TCM software update. It allows the TCM to learn the hydraulic characteristics of the new components.
• GDS2 (or equivalent professional scan tool): Freeze Frame / Failure Records — Crucial for diagnosing intermittent faults. According to TSB 21-NA-003, the technician must check the freeze frame data to see which DTC set first and to analyze the primary and secondary pulley pressure readings at the moment of the fault.
• GDS2 / Multimeter: Solenoid Actuation Test / Command — A bidirectional scan tool can command the solenoid on and off to check for an audible click. This helps determine if the solenoid is mechanically stuck or if the fault is electrical. This can also be done manually by briefly applying 12V to the solenoid terminals.

Wiring & Ground Locations

• Transmission Control Module (TCM) — Located under the left side of the instrument panel, inside the vehicle.. The TCM controls the pressure control solenoid. All wiring for the solenoid originates here, making it a central point for electrical testing (power, ground, signal wires). A poor connection or ground at the TCM can mimic a failed solenoid.
• TCM Ground Pin — At the main connector for the TCM. On many GM modules, the ground wire is a larger gauge wire, often located at the end of a connector row.. A poor ground connection at the TCM itself can cause a host of communication and control issues, including the inability to correctly operate the transmission solenoids, leading to false codes.
• Body Control Module (BCM) Area — In the center console on the front passenger side.. While not the TCM, this location houses major vehicle wiring connections. Damage or corrosion in this central area could potentially affect circuits shared with or routed near the transmission controls.

Real Owner Repair Stories

• Cross-referenced owner forums for similar CVT transmissions (2013 Nissan Sentra with JF015E CVT (similar failure pattern to other CVTs)) — Hesitation between gears during light acceleration, especially after highway driving. Repeatedly logged P0746.
  ❌ Tried (didn't work) Initial thoughts were low fluid or a sensor glitch.
  ✅ What actually fixed it Replacement of the entire transmission valve body assembly. The source noted that replacing only the individual solenoid often leads to a recurrence of the problem, as the root cause is often wear or sludge within the hydraulic passages of the valve body itself.

OEM Part Supersession History

• Varies → Varies — Part revisions to address internal issues.
  Heads up: Multiple part numbers exist for the control valve body assembly across different GM models and production dates (e.g., 24044192, 24044189). It is critical to use the vehicle's VIN and the GM Electronic Parts Catalog (EPC) to order the correct part to ensure compatibility.

Model Year Variations Within This Range

• 2020: TSB 21-NA-003, which details the diagnosis for a sticking pressure regulator valve causing P0746, was revised in May 2022 to specifically remove the 2020 Chevrolet Trailblazer (a platform mate to the Encore GX). While the TSB still applies to the Encore GX, this revision suggests a potential difference in the prevalence or nature of the fault between the two vehicles for that model year.