Error Code P0084: What It Means & What To Do?

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If you are experiencing unusual response of the throttle, lack of power forms the car engine, impact on the fuel economy and frequent illumination of the Check Engine Light, it might be an indication of the OBD Code P0084 error.

OBD-II Code Decreased engine performance is defined as an Exhaust Valve Control Solenoid Circuit

The valve system opens and closes the cylinder at different points in the cycle, for the internal combustion engine to function. On the intake stroke, the intake valves open, allowing air and fuel to enter the cylinder. On the compression and power strokes, both intake and exhaust valves are closed. Finally, on the exhaust stroke, the exhaust valves open to allow the exhaust to escape through the exhaust manifold.

To get the best performance on demand and efficient fuel economy, most modern engines are equipped with a Variable Valve Timing (VVT). Depending on engine speed and load, the engine control module (ECM) adjusts valve timing, some VVT systems affecting only intake valve timing, while others varying both intake and exhaust valve timing. To control valve timing, the ECM modulates a VVT solenoid valve. In turn, the VVT solenoid valve controls engine oil pressure application in the VVT head, mounted on the camshaft. Depending on system design, VVT can advance or retard valve timing.

If the ECM detects a fault in the VVT solenoid valve circuit, such as voltage out of specified range, it will set OBD Code P0084.

What causes the problem of Exhaust Valve Control Solenoid Circuit (Bank 2)?

• Open or short in wiring/harness in relation to the solenoid
• ECM (Engine Control Module) Failure
• Bank 2 Exhaust Valve Control Solenoid is faulty/damaged
• Damaged or broken electrical connector to the solenoid

1. Engine Control Module - Faulty ECM can hamper the exhaust and fuel delivery system. Replace faulty ECM components now!
2. Variable Valve Timing - Faulty VVT will not be able to efficient support the engine’s performance, fuel economy or emissions of the vehicle. Thus, immediately replacement is required.
3. Intake Manifold Solenoid - Damaged solenoids can affect the engine oil pressure application to the VVT head, thus hampering the performance. Replace it now!
4. Diagnostic Tools - It is important to use factory grade diagnostic tools to solve any OBD code error. Buy quality diagnostic and scan tools from us.
5. Engine Control Unit - On very rare occasion the ECU can also be faulty, interpreting the correct input ad faulty. If found faulty, replace it immediately.

This code would be considered a moderately severe issue. This will vary on what symptoms you have and how the fault is actually affecting your vehicle's performance. The fact that its functionality directly influences the exhaust/intake system, makes this an issue you do not want to leave unattended. Neglect this problem long enough, and you could be faced with some hefty engine repair bills.

Common Symptoms

• Check Engine Light and car going into failsafe mode
• Poor acceleration
• Lack of engine power
• Reduced fuel economy
• Increased emission from the exhaust

• Replace/reprogram the faulty ECM
• Fixing poor connection or connectors to the solenoid
• Repair or replace the wiring harness to the solenoid and circuit
• Replacement of failed Bank 2 Exhaust Valve Control Solenoid

A qualified mechanic should use factory grade scan tools to observe any OBD-II error codes that are present and stored in the PCM. These trouble codes have freeze frame data that lets us know under what conditions such as engine load, RPM, speed, and driving time the fault was detected.

• Perform a visual inspection of the wiring harness and electrical connections.
• Next, the scan tool will be used to observe solenoid operation to ensure it is operating properly.
• If the solenoid is within specifications, the ECU will need to be tested. Each manufacturer and model have its own testing procedures to follow for the ECU test. Follow the correct procedure as per the guide manual specific to particular make and model. 

Common mistakes when diagnosing the P0084 code

Some of the common mistakes done while changing diagnosing the OBD code P0084 are:

• Replacing the solenoid directly, without replacing other components
• Not checking for faulty wiring and harness
• Replacing the ECU (Engine Control Unit) directly. 

It is important to follow the diagnostic steps properly and in right order to correct this OBD error and to avoid hefty/costly repairs and also the chances of misdiagnosis causing the OBD error to return again.