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 Aisin AF40 6-speed automatic in 2011-2017 Regal (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 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 (1)
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)
Separate from the well-known low-speed shudder, the VT40 continuously variable transmission suffers hard failures of the line-pressure control solenoid circuit. When the solenoid sticks off, the belt-and-pulley set loses clamping pressure, the transmission cannot transmit torque, and the vehicle abruptly stops accelerating - owners describe engine RPM climbing with no forward motion, or being unable to exceed 20 mph with the pedal floored, sometimes on a highway. Failures are reported between roughly 40,000 and 83,000 miles, and multiple NHTSA complaints describe a second failure after an earlier transmission replacement. Some units have been found with essentially no fluid in the sealed case at teardown.
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
Do not clear the code and keep driving; continued operation with low line pressure destroys the belt and pulleys. Retrieve P2714/P0700 and check line pressure and fluid condition. In GM practice this is almost always resolved by transmission replacement or a remanufactured unit rather than a solenoid-only repair, because by the time the code sets the variator surfaces are already damaged. Insist on documentation of the fluid fill and level check on the replacement unit, since dry-at-delivery units have been reported. Verify powertrain warranty coverage (5yr/60,000 mi) before authorizing repair.
Sources for this issue (3)
First-generation Enclaves (2008-2017) use 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. Failure typically occurs in higher-mileage 2008-2012 builds.
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: Regal, Encore GX, 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.
Looking for P0776 on a different make?
View P0776 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.