Disconnecting your car battery in a Subaru WRX can lead to frustrating resets – lost radio presets, clock settings, and even engine performance data that the car’s computer has learned. Many car owners and even some mechanics attempt to use the OBD2 port to maintain power during a battery change, similar to how it’s done on some other vehicles. However, you might find your WRX OBD2 port “not working” for this purpose. Let’s delve into why this might happen and how to troubleshoot it.
In many vehicles, including the Subaru WRX, pin 16 of the OBD2 port is designed to be constantly powered. The idea is that by connecting a 12V power source to this pin while the battery is disconnected, you can keep the car’s computer and other electronic modules powered up, preventing memory loss. Service centers often use specialized tools that plug into the OBD2 port to do just this, typically protected by a 7.5 Amp fuse.
So, why might your WRX OBD2 port seem “not working” when you try this method? The most common culprit is a blown fuse. While the modules themselves draw minimal power, accessories like interior lights can draw significantly more. If you accidentally open a door, turning on the dome light, while the battery is disconnected and power is supplied only through the OBD2 port, you can easily exceed the 7.5 Amp fuse limit. This fuse is designed to protect the system, and it will blow, effectively cutting off power from the OBD2 port.
When this fuse blows, it’s as if you had simply disconnected the battery without any power maintenance. You’ll notice the same symptoms: your clock and radio reset, and the engine’s computer (ECM) might need to “relearn” its optimal settings, potentially causing a slightly rough idle for a short period. This blown fuse, however, is not related to check engine lights (CELs) and will not trigger one.
The real issue arises when you then try to use your OBD2 port for its primary function – reading diagnostic codes. If the fuse is blown and your code reader relies on the car’s power through the OBD2 port (as many do), it will appear that your OBD2 port is not working at all. The reader won’t power up, and you won’t be able to retrieve any diagnostic information.
Troubleshooting a “Non-Working” WRX OBD2 Port for Power Maintenance:
- Check the Fuse: Locate the fuse box, usually under the dashboard or in the engine bay. Identify the fuse associated with the OBD2 port or accessory power (often labeled “OBD” or “ACC”). Inspect the fuse to see if it’s blown (the wire inside will be broken).
- Replace the Fuse: If the fuse is blown, replace it with a new 7.5 Amp fuse.
- Avoid Accessories: When using the OBD2 port for power maintenance, ensure all accessories are off, and doors are closed to prevent accidental power draw.
- Test with a Code Reader: After replacing the fuse, try your OBD2 code reader to confirm the port is now functional. If it powers up, the blown fuse was likely the issue.
In conclusion, if you’re experiencing a “Wrx Obd2 Port Not Working” situation, especially after a battery disconnect attempt, a blown fuse is the most likely culprit when trying to maintain power. Addressing this simple fuse issue can restore both your power maintenance capability and the diagnostic functionality of your OBD2 port. Remember to be mindful of power draw when using the OBD2 port for battery disconnect power maintenance to prevent future fuse failures.
