P0078, P0079 and P0080: Exhaust valve control solenoid circuit (Bank 1)

If you own a car, you may have encountered a situation where your check engine light comes on and your car displays a DTC code. DTC stands for Diagnostic Trouble Code, and it is a way for your car’s computer to tell you what is wrong with your vehicle. DTC codes are usually composed of a letter and four digits, such as P0078, P0079, or P0080.

In this blog post, we will explain what these DTC codes mean, what are the symptoms and causes of these codes, how to diagnose and repair them, and how to prevent them from happening again. By the end of this post, you will have a better understanding of these DTC codes and how to deal with them.

What are DTC Codes P0078, P0079, and P0080?

DTC codes P0078, P0079, and P0080 are related to the exhaust valve control solenoid circuit (Bank 1). The exhaust valve control solenoid is a device that controls the opening and closing of the exhaust valves in your engine. The exhaust valves are responsible for letting out the burned gases from the combustion chamber into the exhaust system.

• P0078 Exhaust valve control solenoid circuit (Bank 1)
• P0079 Exhaust valve control solenoid circuit low (Bank 1)
• P0080 Exhaust valve control solenoid circuit high (Bank 1)

The exhaust valve control solenoid works by receiving signals from the engine control module (ECM), which is the brain of your car. The ECM monitors various sensors and parameters in your engine, such as the oxygen sensor, the throttle position sensor, the camshaft position sensor, and the crankshaft position sensor. Based on these inputs, the ECM determines the optimal timing and duration of the exhaust valve opening and closing.

The ECM then sends signals to the exhaust valve control solenoid, which converts them into electrical currents that activate or deactivate an electromagnet inside the solenoid. The electromagnet then moves a plunger that pushes or pulls a rod that is connected to the exhaust valve. This way, the exhaust valve control solenoid regulates the amount of air that flows out of the engine.

The exhaust valve control solenoid circuit (Bank 1) refers to the wiring and connectors that connect the ECM to the exhaust valve control solenoid on Bank 1 of your engine. Bank 1 is the side of the engine that contains cylinder 1. Depending on your vehicle’s configuration, Bank 1 may be located on the left or right side of your engine.

DTC codes P0078, P0079, and P0080 indicate that there is a problem with the exhaust valve control solenoid circuit (Bank 1). Specifically:

• P0078 means that there is a low voltage or an open circuit in the exhaust valve control solenoid circuit (Bank 1).
• P0079 means that there is a high voltage or a short circuit in the exhaust valve control solenoid circuit (Bank 1).
• P0080 means that there is an incorrect voltage or a performance issue in the exhaust valve control solenoid circuit (Bank 1).

These DTC codes are usually stored in your car’s computer when it detects an abnormality in the operation of the exhaust valve control solenoid or its circuit. This can affect your engine’s performance and emissions.

What are the Symptoms of DTC Codes P0078, P0079, and P0080?

Some of the common symptoms of DTC codes P0078, P0079, and P0080 are:

• Check engine light on
• Reduced engine power
• Rough idle
• Poor acceleration
• Poor fuel economy
• Increased emissions

These symptoms may vary depending on the severity and frequency of the problem. In some cases, you may not notice any symptoms at all until your car fails an emissions test.

What are the Causes of DTC Codes P0078, P0079, and P0080?

Some of the possible causes of DTC codes P0078, P0079, and P0080 are:

• Faulty exhaust valve control solenoid
• Damaged or corroded wiring or connectors in the exhaust valve control solenoid circuit
• Loose or broken ground wire in the exhaust valve control solenoid circuit
• Blown fuse in the exhaust valve control solenoid circuit
• Faulty ECM

These causes may be due to normal wear and tear, exposure to heat or moisture, physical damage, or electrical interference. In some cases, these DTC codes may be triggered by other problems in your engine or emission system that affect the operation of the exhaust valve control solenoid.

How to Diagnose DTC Codes P0078, P0079, and P0080

To diagnose DTC codes P0078, P0079, and P0080, you will need some tools and equipment such as:

1. A scan tool or code reader
2. A digital multimeter
3. A wiring diagram of your vehicle
4. A repair manual of your vehicle

The diagnosis process involves the following steps:

• Connect the scan tool or code reader to your car’s diagnostic port and retrieve the DTC codes and freeze frame data. Freeze frame data is a snapshot of the engine’s condition when the DTC code was set. It can help you identify the possible causes and conditions of the problem.

• Clear the DTC codes and test drive your car to see if they come back. If they do not come back, the problem may be intermittent or resolved. If they do come back, proceed to the next step.
• Locate the exhaust valve control solenoid and its circuit on Bank 1 of your engine. Refer to the wiring diagram and repair manual of your vehicle for guidance.
• Inspect the exhaust valve control solenoid and its circuit for any signs of damage, corrosion, loose connections, or broken wires. Repair or replace any faulty components as needed.
• Test the exhaust valve control solenoid for resistance and operation using the digital multimeter. Refer to the repair manual of your vehicle for the specifications and procedures. If the solenoid is out of range or does not operate properly, replace it.
• Test the wiring and connectors in the exhaust valve control solenoid circuit for continuity and voltage using the digital multimeter. Refer to the wiring diagram and repair manual of your vehicle for the specifications and procedures. If there is any open or short circuit, repair or replace the wiring or connectors as needed.
• Test the ground wire in the exhaust valve control solenoid circuit for continuity and resistance using the digital multimeter. Refer to the wiring diagram and repair manual of your vehicle for the specifications and procedures. If there is any open or high resistance, repair or replace the ground wire as needed.
• Test the fuse in the exhaust valve control solenoid circuit for continuity and voltage using the digital multimeter. Refer to the wiring diagram and repair manual of your vehicle for the specifications and procedures. If there is any blown fuse, replace it.
• Test the ECM for proper operation using the scan tool or code reader. Refer to the repair manual of your vehicle for the specifications and procedures. If there is any fault in the ECM, replace it.
• Clear the DTC codes and test drive your car to see if they come back. If they do not come back, you have successfully diagnosed and repaired DTC codes P0078, P0079, and P0080. If they do come back, you may have missed something or there may be another problem in your engine or emission system that requires further diagnosis.

How to Repair DTC Codes P0078, P0079, and P0080

To repair DTC codes P0078, P0079, and P0080, you will need some parts and tools such as:

1. A new exhaust valve control solenoid
2. A new fuse
3. A new ECM
4. A scan tool or code reader
5. A digital multimeter
6. A wiring diagram of your vehicle
7. A repair manual of your vehicle
8. Basic hand tools

The repair process involves the following steps:

• Disconnect the negative battery cable to prevent any electrical shocks or damage.
• Remove any components that may obstruct access to the exhaust valve control solenoid and its circuit on Bank 1 of your engine. Refer to the repair manual of your vehicle for guidance.
• Disconnect the electrical connector from the exhaust valve control solenoid.
• Remove the mounting bolts or screws that secure the exhaust valve control solenoid to the engine.
• Remove the exhaust valve control solenoid from the engine.
• Install a new exhaust valve control solenoid in reverse order of removal.
• Reconnect the electrical connector to the exhaust valve control solenoid.
• Reinstall any components that were removed earlier.
• Replace any blown fuse in the exhaust valve control solenoid circuit with a new one of the same rating.
• Replace any faulty ECM with a new one that is compatible with your vehicle’s make and model.
• Reconnect the negative battery cable.
• Clear any DTC codes using a scan tool or code reader.
• Test drive your car to see if DTC codes P0078, P0079, and P0080 are resolved.

How to Prevent DTC Codes P0078, P0079, and P0080

To prevent DTC codes P0078, P0079, and P0080 from happening again, you should follow some preventive measures such as:

• Perform regular maintenance on your car according to your manufacturer’s recommendations.
• Check your engine oil level and quality regularly and change it when needed.
• Check your tire pressure regularly and inflate them to their proper levels.
• Avoid driving over rough roads or hitting potholes or curbs that can damage your wheels and suspension system.
• Avoid exposing your car to extreme temperatures or humidity that can affect your electrical system.
• Have your car inspected by a professional mechanic regularly and fix any problems as soon as possible.

Conclusion

DTC codes P0078, P0079, and P0080 are related to the exhaust valve control solenoid circuit (Bank 1). These codes indicate that there is a problem with the voltage or performance of the solenoid or its circuit. The solenoid is a device that controls the opening and closing of the exhaust valves in your engine, which affects your engine’s performance and emissions.

Some of the symptoms of these codes are check engine light on, reduced engine power, rough idle, poor acceleration, poor fuel economy, and increased emissions. Some of the causes of these codes are faulty solenoid, damaged wiring or connectors, loose or broken ground wire, blown fuse, or faulty ECM.

To diagnose these codes, you need to use a scan tool or code reader, a digital multimeter, a wiring diagram, and a repair manual. You need to check the solenoid, the wiring and connectors, the ground wire, the fuse, and the ECM for any faults and repair or replace them as needed.

To repair these codes, you need to replace the solenoid, the fuse, or the ECM with new ones. You also need to clear the codes using a scan tool or code reader and test drive your car to see if the problem is resolved.

To prevent these codes from happening again, you need to perform regular maintenance on your car, check your engine oil and tire pressure regularly, avoid driving over rough roads or hitting potholes or curbs, avoid exposing your car to extreme temperatures or humidity, and have your car inspected by a professional mechanic regularly.

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