P0084 trouble code definition
P0084 is a general code indicating an issue with the exhaust valve control circuit on the bank 2 side of the engine.
This code is similar to P0085 and P0086. The engine also has a bank 1 exhaust control solenoid.
What the P0084 code means
P0084 is a generic OBD2 code that is indicating a fault has been found in the exhaust valve control solenoid. The exhaust valve control solenoid is part of the variable valve timing system.
P0084 code is set when the ECU tries to control the exhaust valve timing on bank 2 and detects a fault. This fault triggers a Check Engine Light to be seen on the dashboard and a failsafe mode to be activated. Variable valve timing is also disabled due to the failsafe.
What causes the P0084 code?
A multitude of issues can cause P0084, here are the most common:
- Open or short in wiring harness
- ECM that has failed
- Bank 2 exhaust valve control solenoid is faulty
- Damaged or broken electrical connector or poor electrical connection
What are the symptoms of the P0084 code?
Symptoms are generally mild with P0084, after the Check Engine Light is triggered it should be not be a problem to drive to a safe location.
A Check Engine Light being illuminated on the dashboard will be the first noticed symptom.
Once the Check Engine Light has been triggered the car will go into a failsafe mode to prevent damage.
With this trouble code, poor vehicle acceleration and lack of power may be noticed. In addition, you may notice poor gas milage.
How does a mechanic diagnose the P0084 code?
A qualified mechanic will begin by hooking up a scan tool to observe any OBD2 codes that are present. These trouble codes will have freeze frame data that lets us know under what conditions such as engine load, RPM, speed, and driving time the fault was detected at.
The codes will then be cleared and a road test is performed under similar conditions to the freeze frame data. If P0084 reappears during the test drive further diagnosis will be needed.
A technician will now 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 has its own testing procedures to follow for the ECU test.
Common mistakes when diagnosing the P0084 code
The most common mistake during diagnosis of P0084 is replacing the solenoid before any other testing has been performed.
Although the solenoid is the most common cause of P0084 all steps must be followed and not skipped to accurately fix the vehicle.
How serious is the P0084 code?
P0084 is a common code that is seen with vehicles as they age. Vehicle operation may be hindered by the lack of power, worse acceleration and fuel economy will suffer. These issues should be fixed as soon as possible for safe driving and normal vehicle operation.
What repairs can fix the P0084 code?
- Replacing the ECM
- Fixing poor connection or connectors
- Repairing or replacing the wiring harness
- Replacing a failed bank 2 exhaust valve control solenoid
Additional comments for consideration regarding the P0084 code
Bank 2 should be on the passenger side of the engine. The exhaust valve control solenoid should be found near the exhaust manifold.
Scan tools with the capability to view live data and graph information changes over time will be needed to properly diagnose P0084. This is especially true when the issue is intermittant and tough to detect without a scan tool.
Need help with a P0084 code?
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This article originally appeared on YourMechanic.com as P0084 OBD-II Trouble Code: Exhaust Valve Control Solenoid Circuit (Bank 2) and was authored by Spencer Clayton.