Disconnecting your car battery in a 2015 Subaru WRX, even for routine maintenance, can lead to more than just a reset clock. Modern vehicles, including the 2015 WRX, rely on constant power to maintain settings within various control modules. This “learned” data optimizes your car’s performance and ensures systems operate smoothly. When power is lost, these settings are wiped, alongside your radio presets and clock. For 2015 WRX owners, understanding how the OBD2 port plays a role in this process is crucial, especially when it comes to battery maintenance.
The challenge with Subarus, unlike some other makes, is that the accessory power outlets are not constantly powered. This means you can’t simply plug in a 12V supply there to maintain memory while changing the battery. However, the On-Board Diagnostics II (OBD2) port offers a solution. Specifically, pin 16 of the OBD2 connector is designed to be always hot, providing a direct connection to the car’s electrical system, even with the ignition off.
This constant power supply at the 2015 Wrx Obd2 Port’s pin 16 makes it an ideal point for connecting a temporary external power source during battery changes. Many automotive service centers utilize specialized OBD2 adapters connected to a 12V power supply, like a portable jump starter, to prevent memory loss. They often incorporate a 7.5 Amp fuse in these adapters for safety.
This method works effectively because the power draw from the control modules needing to retain memory is minimal. The 7.5 Amp fuse is usually sufficient for this low current draw. However, it’s critical to ensure that no other electrical systems in the 2015 WRX are activated during this process. A common mistake is opening a door, which can trigger interior lights and other systems. If the total current draw exceeds 7.5 Amps while the car battery is disconnected and power is being supplied through the OBD2 port, this fuse will blow. The consequence is the same as if no memory saver was used at all – lost presets and potentially a temporarily rough idle as the engine control module (ECM) relearns its parameters.
Therefore, if you find your radio presets and clock reset after a battery replacement on your 2015 WRX, it’s possible a fuse related to a memory-saving attempt through the OBD2 port might have blown. While this fuse issue itself won’t trigger a check engine light (CEL), it’s worth noting that a blown fuse in this circuit can prevent some OBD2 code readers, particularly those relying on vehicle power, from functioning. They simply won’t receive the necessary power through the OBD2 port to operate and read diagnostic trouble codes. Understanding the power dynamics of your 2015 WRX OBD2 port is key to successful battery maintenance and preventing unintended memory loss.
