EngineLightCodes
Powertrain code

P0779 Pressure Control Solenoid B Intermittent

Severity
Fix soon
Typical repair cost
$110–$2,200
Do it yourself
Shop job
Shop time
1–5 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

In J2012 P0779 is an intermittent fault of valve B. The only manufacturer use found differs: Mitsubishi's 2022 Jatco CVT sets P0779 for an open circuit or short to positive in the secondary pressure valve circuit after 1 s (short to ground is P0778). The transmission then engages harshly, accelerates weakly and does not lock up.

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

Symptoms

  • Harsh engagement at times
  • Weak acceleration, no lock-up
  • Check engine light

Common causes

  1. Connector or wire open or loose contact Most likely
  2. Short to positive in the harness Possible
  3. Valve coil faulty Possible

How to diagnose P0779

  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.

Reading the code

P
Powertrain
0
Generic (SAE) code
7
Transmission
79
Specific fault

Questions drivers ask

Can I drive with code P0779?

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 P0779?

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.

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.