OBD-II Code · Powertrain
P0777
Pressure Control Solenoid "B" Stuck On
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$400–$3,000
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
EPC solenoid B stuck on (full pressure).
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Very firm/harsh shifts
- Possible burnt fluid
Likely causes
- Stuck solenoidMost common
- Debris in valve body
Read the full diagnostic procedureP0777 means Pressure Control Solenoid B is stuck on, i.e., the PCM has determined the solenoid is delivering maximum pressure regardless of duty-cycl…
P0777 means Pressure Control Solenoid B is stuck on, i.e., the PCM has determined the solenoid is delivering maximum pressure regardless of duty-cycle command, or that commanded pressure changes produce no hydraulic response in the stuck-high direction.
Cheapest-first
- connect a scan tool, command EPC duty-cycle changes (or current changes on current-controlled systems), and watch line pressure on a mechanical gauge at the test port.
- If line pressure stays pegged at the high end (for example, 240 to 280 psi on 4L60E full-throttle pressure regardless of command), the solenoid plunger is mechanically stuck or the regulator valve is jammed.
- Measure solenoid resistance to confirm it is not electrically shorted (spec typically 3 to 7 ohms for GM force motors, 4 to 6 ohms for Toyota/Ford PC solenoids).
- Drop the pan and inspect for contamination: P0777 is frequently caused by a single piece of clutch debris or a broken check ball wedged in the solenoid screen or bore.
- Inspect the pressure regulator and boost valves for sticking with a flashlight and pick.
- Caveat: a stuck-on PC solenoid produces extremely harsh shifts that can quickly damage clutches, so do not drive the vehicle hard while diagnosing; tow if shifts are jarring.
Vehicle-specific patterns2000 to 2006 Chevrolet Silverado with 4L60E sets P0777 from debris from a failing 3-4 clutch wedging in the EPC screen, with GM PIP3911 calling for s…
- 2000to 2006 Chevrolet Silverado with 4L60E sets P0777 from debris from a failing 3-4 clutch wedging in the EPC screen, with GM PIP3911 calling for solenoid and filter replacement plus pan flush.
- 2003to 2008 Dodge Durango with 545RFE trips P0777 from line pressure solenoid contamination inside the solenoid pack, requiring full pack replacement per Chrysler TSB 21-010-08.
- 2004to 2009 Toyota 4Runner with A750F sets the SLT stuck-on equivalent from internal varnish, typically after extended fluid intervals.
- 2005to 2011 Nissan Frontier/Xterra with RE5R05A trips the equivalent code from the line-pressure solenoid contamination and stepped valve body wear.
Estimated repair$280 to $1,500.
Look up another code
P0777 — frequently asked
What does a P0777 code mean?
EPC solenoid B stuck on (full pressure).
What causes a P0777 code?
Common causes: Stuck solenoid; Debris in valve body.
What are the symptoms of a P0777 code?
Typical symptoms: Very firm/harsh shifts; Possible burnt fluid.
Is it safe to drive with a P0777 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $400-$3,000.
How do I diagnose a P0777 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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