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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.
The PCM stores the P0778 code when an abnormal voltage reading is detected from the electronic pressure control solenoid, or the correlating circuit.
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.
Common causes may include:
The symptoms that can accompany the P0778 code can vary greatly. In addition to the illuminated Check Engine lamp, drivers may observe:
In addition, there may be other torque converter clutch, gear ratio, lock up, shift solenoid, or transmission slippage codes stored with 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.
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.
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.
Common repairs may include:
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