Engine-CodesInfiniti – P0778 Infiniti

P0778 Infiniti Code - Pressure Control Solenoid 'B' Circuit

Quick Answer

The P0778 Infiniti code refers to a problem with the Pressure Control Solenoid 'B' circuit in the vehicle's transmission system. Common causes include Faulty pressure control solenoid 'B', Wiring or connector issues in the solenoid circuit, Low transmission fluid levels or dirty fluid. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0778 Infiniti indicates Pressure Control Solenoid 'B' Circuit.
Common causes
Common causes include Faulty pressure control solenoid 'B', Wiring or connector issues in the solenoid circuit, Low transmission fluid levels or dirty fluid.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 11, 2024
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Code P0778 Infiniti Description

The P0778 Infiniti code refers to a problem with the Pressure Control Solenoid 'B' circuit in the vehicle's transmission system. The pressure control solenoid is responsible for regulating the hydraulic pressure in the transmission, which is crucial for smooth shifting and overall performance. When this solenoid malfunctions or the circuit that controls it has issues, it can lead to a range of transmission problems that can affect the vehicle's drivability and performance.

OBDII Code P0778 Infiniti - Pressure Control Solenoid 'B' Circuit
P0778 Infiniti Code - Pressure Control Solenoid 'B' Circuit

Common Causes of P0778 Infiniti

  1. Faulty pressure control solenoid 'B'
  2. Wiring or connector issues in the solenoid circuit
  3. Low transmission fluid levels or dirty fluid
  4. Internal transmission damage
  5. ECM or TCM (transmission control module) malfunction

Symptoms of P0778 Infiniti

  1. Harsh or delayed shifting
  2. Transmission slipping
  3. Erratic shifting behavior
  4. Illuminated check engine light
  5. Decreased fuel efficiency

How to Fix P0778 Infiniti

  1. Begin by diagnosing the specific cause of the issue using a professional diagnostic scanner to pinpoint the exact problem.
  2. Inspect the pressure control solenoid 'B' and its wiring for any signs of damage or wear. Replace the solenoid if necessary.
  3. Check the transmission fluid level and condition. Top up or replace the fluid if it is low or contaminated.
  4. Test the ECM and TCM for proper operation. Replace or reprogram these modules if they are found to be faulty.
  5. Clear the fault code and test drive the vehicle to ensure that the issue has been resolved.

Cost to Fix P0778 Infiniti

The cost of repairing a pressure control solenoid 'B' circuit issue can vary depending on the specific cause of the problem and the labor rates in your area. In general, you can expect to pay anywhere from $200 to $500 for parts and labor for this repair. Keep in mind that additional costs may apply if other transmission components need to be replaced or if further diagnostics are required. It is recommended to consult with a professional mechanic or auto repair shop for a more accurate cost estimate based on your vehicle's make and model.

Tech Notes for P0778 Infiniti

When a transmission solenoid is malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure and that the transmission will need to be rebuilt or replaced.

When is the Code Detected?

Engine Control Module (ECM) detectes an open or shorted condition on the solenoid circuit

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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