P0777: Pressure Control Solenoid B Stuck On
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Briefly - a solenoid stuck on applies pressure out of turn, and the binding or harsh engagement it causes loads the drivetrain. If engagement turns violent, stop.
Symptoms
- Wrong gear for the speed
- Harsh or clunking engagement
- Binding feel in some gears
- Limp mode holding a single gear
Likely causes, most common first
- Solenoid B jammed on by debris
- Valve stuck applied in the valve body
- Contaminated fluid
- Cross-leak pressurizing the circuit
Read P0777 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0777 is solenoid B's stuck-on variant: pressure present where none was commanded. Its character differs from the stuck-off codes - instead of slip, the transmission applies a clutch at the wrong moment, felt as clunks, a bind in certain gears, or the engine lugging against a gear it never asked for.
Mechanically this is almost always contamination wedging the solenoid or its valve in the applied position, which is why the fluid-first rule holds even more strongly here: what jammed it arrived through the fluid. The caution from this code's cousins bears repeating - wrong-time clutch application shock-loads axles, mounts and the transmission case itself, so harsh clunks are a reason to shorten the diagnosis timeline, not to acclimate to the noise.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0777
“The contact owns a 2021 GMC Yukon. The contact stated that while driving at an undisclosed speed, the vehicle would independently activate Limp mode and would not accelerate past 30 MPH. In addition, the vehicle would not shift into the Reverse gear as intended. The vehicle was taken to a local dealer, where it was diagnosed with error codes: P0777 and P18A1. The vehicle was not repaired due to parts being on backorder. Upon further investigation, the contact related the failure to an Unknown NHTSA Campaign; however, the VIN was not included. The manufacturer was made aware of the failure. The failure mileage was approximately 90,000.”2021 GMC Yukon · May 2026 · 90,000 mi
“My car lost all power on a bridge and started jerking me forwards and backwards. High RPMS and eventually lost reverse. Code number p0777. Seems aligned with the newest transmission recall, but my vin is not listed.”2022 GMC Yukon XL · Mar 2026
“Car went to limp mode, hard shifting very suddenly. Transmission system failed. No reverse. Computer codes p0700 p0777 p18A1 inspected at Chevy service center and needs valve body replacement. No warnings, lights, alerts, hard shifts previously.”2022 Chevrolet Tahoe · Dec 2025
Show 7 more owner reports
“The contact owns a 2019 Honda Pilot. The contact stated that the engine light was illuminated. The transmission emission message was displayed. The contact stated that the failure was associated with DTC: P0777. The vehicle was taken to the local dealer, who recommended a transmission flush. After the transmission flush the vehicle failed to shift from second to third gear. The vehicle was taken to the dealer a second time and another transmission flush was recommended and the dealer eventually determined that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was contacted, and a case was filed. The failure mileage was approximately 124,000.”2019 Honda Pilot · Jul 2025 · 124,000 mi
“Vehicle stalled with no warning signs while I was driving and went into limp mode, took it to a jeep dealer to check it out. They say the jeep needs a whole new transmission. Will not drive at all but has power. Only has 112,000. Codes: p0777 - pressure control solenoid b - stuck on, p0741 - torque converter clutch solenoid - stuck off, p0730 incorrect great ratio”2016 Jeep Patriot · Jan 2021 · 112,000 mi
“Code p0777 pressure control solenoid b stuck on car is not going into gears now. First, it would only go into reverse. But, nothing now.”2016 Jeep Patriot · Jan 2020 · 97,470 mi
“Tl* the contact owns a 2013 jeep patriot. The contact stated that while attempting to traverse a hill, the transmission failed to shift as intended. The contact stated that the vehicle started to overheat and the speed was reduced independently. The contact also stated that the vehicle failed to exceed 40 mph with the accelerator pedal depressed. The vehicle was taken to an unknown mechanic that located failures codes p0777 and p0741. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage 107,000.”2013 Jeep Patriot · Jul 2019 · 107,000 mi
“Car is unable to transfer to higher gears. Error code p0730 and p0777. 84k miles. Two shops stating new transmission needed.”2012 Jeep Patriot · Mar 2019
“Http://repairpal.com/transmission-fault-andor-check-engine-light-with-code-p0716-p0776-p0717-p0777-p2714-p2715-an-567 how is the transmission not being recalled! Someone is going to get seriously hurt. Does it take a death before anything is done? Good grief!! *tr”2008 Saturn Vue · Sep 2014 · 74,000 mi
“Transmission 35r clutch wave plate failure requires complete transmission rebuild. Vehicle was properly maintained at appropriate service intervals. Transmission started to slip when shifting from 3rd to 4th gear and hesitated to up shift from 5th to 6th gear. Trouble codes p0700 and p0777 were logged when transmission first slipped. *tr”2008 Saturn Vue · Aug 2013 · 88,000 mi
Cars that report P0777 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0777?
Briefly - a solenoid stuck on applies pressure out of turn, and the binding or harsh engagement it causes loads the drivetrain. If engagement turns violent, stop.
How much does it cost to fix P0777?
Typical US repair costs range from $150 for the simplest fix (transmission fluid and filter service) to $1,500 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0777. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.