EngineLightCodes
Powertrain code

P0777 Pressure Control Solenoid B Stuck On

Severity
Fix soon
Typical repair cost
$440–$5,500
Do it yourself
Shop job
Shop time
2–14 hours

Pressure control solenoids are current-controlled proportional valves, and what B and C mean depends on the design: on GM's clutch-to-clutch automatics they are the pressure valves of clutches 2 and 3, on GM's CVT B is primary pulley pressure and C line pressure, on Jatco CVTs B is the secondary pressure valve, on Saab's AF40 B and C are clutch valves SLC1/SLC2.

How the engine computer detects it

P0777 means the valve is electrically fine but pressure stays applied – the off-going clutch does not release. GM's 9-speed flags clutch 2 slip below 50 rpm for 0.8 s on loaded downshifts, the 8-speed uses a torque and inertia phase test, Allison 25 rpm or less – all after one trip. GM's Honda-built five-speed cannot always separate it from P0746 and stores both. Harsh shift jolts, tie-up and a default gear follow.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Harsh shift jolt, transmission ties up
  • Limp mode in a fixed gear
  • Check engine light

Common causes

  1. Spool or pressure valve sticking Most likely
  2. Clutch stuck or piston hanging Possible
  3. Contaminated fluid (debris after clutch damage) Possible
  4. Software or false setting Less likely

How to diagnose P0777

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: pressure control solenoid, transmission valve body, transmission clutches, transmission control module.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Vehicles that report P0777 most

VehicleYearsReportsMedian miles
Jeep Patriot2012–20164107k
Saturn Vue2008388k

Counts of owner complaints to the NHTSA that mention P0777 (19 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.

Reading the code

P
Powertrain
0
Generic (SAE) code
7
Transmission
77
Specific fault

Questions drivers ask

Can I drive with code P0777?

Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.

Will my car pass an emissions inspection with P0777?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

Often reported together

Codes that owners mention in the same NHTSA complaints as P0777. They can point to a shared cause, so it's worth checking them together.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.