P0778 OBD-II Trouble Code: Pressure Control Solenoid B Electrical

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0778 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0778 code

P0778 is a diagnostic trouble code (DTC) for "Pressure Control Solenoid B Electrical". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0778 DIAGNOSTIC Get a fair and transparent estimate upfront

P0778 code definition

The PCM stores the P0778 code when an abnormal voltage reading is detected from the electronic pressure control solenoid, or the correlating circuit.

What the P0778 code means

In order to operate the engine efficiently, the PCM monitors the fluid pressure from a variety of sensors within the engine. For every specific driving condition, there is a preset manufacturer specification that tells the PCM what the voltage reading should be to ensure optimal fluid pressure. If the pressure control solenoid does not report the proper voltage reading, the PCM assumes a problem with the engine fluid pressure, and stores the P0778 code.

What causes the P0778 code?

Common causes may include:

  • Faulty electronic pressure control solenoid B, or solenoid B valve
  • Blocked transmission fluid passages
  • Internal transmission failures
  • Low transmission fluid, or dirty or contaminated transmission fluid
  • Faulty electrical components within the pressure control solenoid B

What are the symptoms of the P0778 code?

The symptoms that can accompany the P0778 code can vary greatly. In addition to the illuminated Check Engine lamp, drivers may observe:

  • Inability to shift gears
  • Harsh shifting
  • Slipping transmission
  • Overheated transmission
  • Decreased fuel economy
  • Failure of the torque converter clutch to either engage or disengage

In addition, there may be other torque converter clutch, gear ratio, lock up, shift solenoid, or transmission slippage codes stored with the P0778 code.

How does a mechanic diagnose the P0778 code?

After an OBD-II scanner detects the P0778 code, there are two things that the technician should turn to first: a visual inspection of all electrical wiring, connectors, and harnesses, and a visual inspection of the transmission fluid. Any damaged or loose electrical components should be replaced; contaminated transmission fluid should be flushed, and the system should be refilled with clean fluid.

These are two very common and relatively inexpensive repairs that can cause this code. After these, and each subsequent repair, the mechanic should clear the PCM and retest the system. If the P0778 code returns, then the mechanic should begin testing the solenoid and other potentially faulty components, until the fault is found.

Common mistakes when diagnosing the P0778 code

The most common mistake made during the diagnostic process for the P0778 code is replacing the high pressure pump, rather than checking for faulty solenoids or wiring.

How serious is the P0778 code?

The P0778 code represents a serious drivability issue. Without the ability to monitor and actuate changes within the engine fluid pressure, the vehicle may not operate safely or optimally. It is important to have this repair done as soon as possible after detecting this code.

What repairs can fix the P0778 code?

Common repairs may include:

  • Replacing a faulty electronic pressure control solenoid B, or solenoid B valve.
  • Clearing and refilling blocked transmission fluid passages.
  • Addressing any internal transmission failures.
  • Refilling low transmission fluid, or replacing dirty or contaminated transmission fluid.
  • Repairing or replacing any faulty electrical components within the pressure control solenoid B.

Need help with a P0778 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6220.

P0778
trouble codes
Check Engine Light

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0778 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

4,810

Rating Summary
4,424
187
47
28
124
4,424
187
47
28
124

Joel

19 years of experience
741 reviews
Joel
19 years of experience
Acura RL - Check Engine Light is on - Jacksonville, Florida
very knowledgeable and precise. able to fix electrical issues in my car. Right on time for the appointment.

Christopher

15 years of experience
41 reviews
Christopher
15 years of experience
Honda Accord - Check Engine Light is on - Fairburn, Georgia
Christopher was excellent! He explained everything in detail to make sure I understood. He was professional and provided me with the next course of actions to resolve my care issues. I'm glad he was sent to service my car.

Alexander

18 years of experience
58 reviews
Alexander
18 years of experience
Saab 9-7x - Check Engine Light is on - Kissimmee, Florida
He was very friendly and very helpful . I felt like it was being around a close friend , also gave me so very good advice on my car & future advice about it . Highly recommend mechanic, would use his services again .

Matthew

31 years of experience
639 reviews
Matthew
31 years of experience
Jeep Patriot - Check Engine Light is on - Norfolk, Virginia
Matthew was on time which was a relief, he is very knowledgeable and was easy to understand what was wrong and what was being done. I am recommending to friends and family due to the great experience Matthew gave me. Extremely professional 10/10

More related articles

Related questions

Start up is okay. Blue smoke, rough idle, and stalling. Cannot rev motor. (2002 Nissan Elgrand)

The blue smoke is due to oil leaking into the combustion chambers. The cause can vary from fairly easy to fix worn out valve stem oil seals to more costly faults such as leaking piston rings or head gasket failures....

Check engine light - O2 sensor circuit + speed sensor circuit...

Hi there. O2 sensor low voltage can be caused my a number of things. Mass air flow sensor was only one of them. It can be a bad O2 sensor, coolant temperature sensor, or wiring issue. What should be...

Vehicle turns off at any rpm, at idle or highway speeds, without stumbling or warning.

This kind of a stalling issue can be caused by a variety of problems. They are typically caused by ignition faults, wiring faults, and fuel issues. Although you do not have a Check Engine Light on, you should still scan...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com