What Is the P0778 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
Get Additional Help
P0778 is a diagnostic trouble code (DTC) that indicates electrical damage or malfunction in the pressure control solenoid B (PCS B). The generic transmission code is typically set by the transmission control module (TCM) or the powertrain control module (PCM) in some cars.
The P0778 OBD-II trouble code is commonly associated with automatic transmissions and may present a whole host of complications.
Who Has the Lowest Price?
Some service centers will give you an online estimate to compare. Why drive around Town!?
What Are the Symptoms of a P0778 Code?
The pressure control solenoid B is an essential component of the transmission system. As such, any electrical issues within it will have a noticeable effect on the vehicle.
Once the PCM/TCM detects the error, the check engine light will come on. You will also start experiencing issues with the transmission, such as:
- Harsh shifts
- Delayed gear shifts
- Overheated transmission due to the increased friction
- Transmission slippage, where the transmission struggles to maintain the selected gear
- Poor fuel economy – You will notice that the vehicle guzzles more gas with this code. This is primarily due to the inefficiencies within the transmission, which puts more load on the engine.
It is important to note that the above symptoms are not unique to a P0778 code and are standard with all other transmission codes like generic code P0745. Nonetheless, they are a good place to start when diagnosing the exact problem.
What Are Some Causes of a P0778 Code?
Fault code P0778 is primarily caused by any form of electrical malfunction that affects the B pressure solenoid. The solenoid is a vital component of the transmission and plays a crucial role in regulating the hydraulic pressure within the system.
Additionally, the B solenoid controls the clutch plates in the transmission and ensures they provide the required gear ratios. The PCS B is constantly exchanging electrical signals with the TCM and contains different components. Thus, any fault in the electrical circuit between the PCM and PCS B causes communication issues and triggers code P0778. Common culprits include:
- Frayed wiring
- Loose connections
- Faulty wiring harness
- Damaged or missing connector pins
- Bad wiring
Although DTC P0778 signifies an electrical issue, there are lots of other factors that can trigger it. For instance, a low transmission fluid level can severely affect the solenoid’s functions and activate the code. Other issues include a defective transmission valve body or a faulty TCM.
How Serious Is the P0778 Code?
A P0778 code can worsen with time, depending on the root cause of the problem and how you handle the car.
Although the code does not directly affect the engine, problems with the pressure control solenoid can severely damage your car’s transmission.
This, and other factors like the erratic shifts and slipping gears, may not only increase your chances of a collision but also damage your clutch packs and the gearbox. As such, all P0778-related problems should be handled by certified mechanics.
Can I Still Drive with a P0778 Code?
Just because a P0778 Code will not immediately paralyze your vehicle does not mean that it won’t do so. To avoid painful surprises and excessive repair costs, avoid driving the car for long distances until you get a clean bill of health from your mechanic.
Driving with an active P0778 code also presents plenty of drivability issues, including delayed shifts, limp mode, engine misfires, and poor fuel economy. If you must drive the car, maintain a low speed to reduce the strain on the transmission and avoid busy highways.
How Easy Is It to Diagnose a P0778 Code?
A P0778 code can be challenging to diagnose as it requires more than an onboard scan tool or code reader. To minimize the risk of misdiagnosis, it is best to seek help from an experienced mechanic.
The first step is usually a visual inspection to identify the faulty components and missing parts. The mechanic will also inspect the transmission for any leaks, external damage, and signs of overheating. If no defects are apparent, they will check if the problem was due to a failing transmission pump or dirty transmission fluid.
An inspection of the electrical wiring and circuits is also necessary to check for damage, corrosion, or loose connections. This is where the multimeter and other electrical diagnosis tools come in handy. They help analyze voltage and resistance readings.
Additional tests and checks may include solenoid testing, line pressure testing, and valve body testing.
How Difficult Is It to Inspect a P0778 Code?
If you take your car for inspection as soon as you identify the problem, the repair process will be easier. The extent of the damage will likely be moderate or minimal. Common repairs for electrical error code P0778 include:
- Replacing contaminated transmission fluid and filter
- Replacing the wiring in the circuit,
- Transmission flush.
If the problem is severe, you may need to do a transmission replacement or get a new PCS B. The average estimate for replacement transmissions is relatively high, regardless of the model of the vehicle or service center you visit.
Need Additional Help with Your P0778 Code?
A P0778 code is a potentially serious issue that requires urgent and professional expertise. Use KBB.com to discover and locate credible service centers in and around your area.
P0778 Q&A
Common Error Codes
Browse All OBD-II Codes
Get Recall Alerts
All recalls are considered serious. Stay safe. Take care of any recalls ASAP. The good news? Recall repairs are free when performed at a local dealer.