P0776 on Buick: How to Diagnose & Fix
Pressure Control Solenoid B Performance/Stuck Off
3 Buick models · 4 documented issues · 3 critical · $150-$7,800 repair
P0776 on Buick by model: symptoms, diagnosis and fix
The VT40 CVT can lose forward gear, slip or lose propulsion with the check-engine light on. GM lists a pressure regulator or clutch regulator valve sticking in the valve body, forward clutch piston damage, or wear in the primary pulley bearing bore as causes; running in this state can damage the drive chain and pulleys. Applies to: 2020-2024 Buick Encore GX with the VT40 CVT (bulletin 21-NA-003) and 2020-2025 (bulletin 24-NA-009): front-wheel-drive models with the 1.2L LIH or 1.3L L3T. Not the AWD 9-speed automatic.
Common Symptoms
- Vehicle will not accelerate past ~20 mph with pedal fully depressed
- Engine revs but vehicle does not move
- Delayed engagement when shifting into Drive or Reverse
- Loud whine or mechanical noise from the transaxle
- Sudden jerk followed by loss of drive at highway speed
- Speedometer rising and falling erratically
How to Fix
Under these bulletins, a technician first inspects the drive chain and pulleys with a borescope (bulletin 20-NA-120); if they are damaged the transmission is replaced. Otherwise the valve body, pressure sensors or solenoid body are replaced according to the codes and pulley pressures, and with loss of drive, slipping or burnt fluid the transmission is disassembled to repair the forward clutch or replaced if the primary pulley bearing bore is worn. Normal warranty rules apply; this is not a recall or a promise of free repair.
Sources for this issue (4)
Regals equipped with the GM 6T40/6T70 six-speed automatic can develop torque-converter shudder, slipping or flare on the 2-6 shift, and harsh/delayed shifts. The 6T40 issue is commonly debris blocking the 2-6 clutch regulator valve circuit; the 6T70 suffers wear in the accumulator/solenoid valve bores and torque-converter clutch shudder, sometimes worsened by overheated, degraded fluid.
Common Symptoms
- Shudder/vibration under light acceleration
- Slipping or RPM flare between gears
- Hard or delayed shifts
- Surge when shifting into/out of 2nd or 6th
How to Fix
Start with a full transmission fluid/filter service (fixes many shudder cases). Persistent problems require valve body cleaning/rebuild, accumulator bore repair, or torque converter replacement. Use only the correct GM spec fluid.
Sources for this issue (1)
The Aisin AF40 6-speed automatic in 2011-2013 Regal 2.0L Turbo (and 2010-2017 LaCrosse 4-cyl, 2008-2017 Opel Insignia A) develops harsh 1-2 and 2-3 shifts, torque-converter shudder at light throttle, and delayed engagement, usually at 80,000-150,000 miles. GM's "lifetime fill" claim is widely disputed by independent shops.
Common Symptoms
- harsh shifts
- torque converter shudder
- delayed engagement
- flare on upshift
How to Fix
Drain-and-fill ATF every 50,000 miles using AC Delco / Aisin AFW+ (or JWS3309 equivalent) — about $150-$250 DIY (5-6 qt drained per service). Severe shudder may need torque converter or valve body work ($1,500-$3,500). If neglected past 120k miles, full rebuild may be required ($3,500-$5,500).
Sources for this issue (2)
The first-generation Enclave (built 2008-2017) uses the 6T70/6T75 6-speed automatic, whose stamped-steel 35R wave plate can crack at the teeth after enough shift cycles. When it fractures, the transmission abruptly loses 3rd, 5th, and reverse gears, and debris can damage the valve body, drums, and torque converter. GM's bulletin and special coverage for this failure cover 2008-2009 Enclaves.
Common Symptoms
- Sudden loss of 3rd, 5th and reverse gears
- Slipping or no movement
- Harsh or no shifts
- Check engine / transmission warning light
How to Fix
Disassemble and rebuild the transmission with an updated/stronger wave plate, plus replace damaged hard parts and clean out debris; in severe cases a remanufactured unit is installed.
Sources for this issue (2)
P0776 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0776 mean on a Buick?
P0776 stands for "Pressure Control Solenoid B Performance/Stuck Off." This code means the transmission's Pressure Control Solenoid B is not performing correctly and is behaving as if stuck in the 'off' position. Pressure control solenoids regulate the hydraulic fluid pressure used to apply clutches and bands and to control shift quality, so when one underperforms the transmission may shift harshly, slip, flare between gears, or feel inconsistent. The transmission control module sets this code when the fluid pressure or response it measures doesn't match what it commanded from that solenoid. It generally indicates a hydraulic performance issue with the solenoid or its fluid circuit rather than just a wiring fault. On Buick it is documented across 3 models: Encore GX, Regal, Enclave.
What are the most common causes of P0776?
The most common causes of P0776 are: Stuck or failed pressure control solenoid B, Low, dirty, or degraded transmission fluid, Clogged solenoid screen or valve body passages, Sticking or worn valve body components, Wiring or connector problem at the solenoid, Internal transmission wear or pressure loss, Faulty transmission control module. The specific cause varies by vehicle.
How much does it cost to fix P0776 on a Buick?
Published repair estimates on Buick range from $150 to $7,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.