Maintaining your 2011 Subaru Impreza’s computer settings when disconnecting the battery is a common concern for car owners and DIY mechanics. When battery power is lost, several control modules in your Impreza, including the ECU (Engine Control Unit) and radio, can lose their “learned” data. This can result in lost radio presets, clock settings, and even temporary rough idling as the engine management system relearns optimal parameters.
While some vehicles allow for maintaining power through accessory power outlets during a battery change, Subaru Imprezas, including the 2011 model, do not offer this convenience as their outlets are not constantly powered. Fortunately, there’s another solution readily available in your vehicle: the OBD2 port. Pin 16 of the OBD2 (On-Board Diagnostics II) connector in your 2011 Subaru Impreza is designed to be always hot, meaning it receives constant power directly from the battery. This makes it a viable point to connect an external 12V power source to preserve your car’s memory settings while the main battery is disconnected.
The OBD2 port in a 2011 Subaru Impreza is typically located beneath the dashboard on the driver’s side. You’ll usually find it in the vicinity of the steering column, often near the hood release lever. Its standardized trapezoidal shape and 16 pins make it easily identifiable.
Many automotive service centers utilize specialized OBD2 memory saver adapters for this purpose. These adapters, often connected to a portable jump starter or another 12V battery source, plug directly into the OBD2 port. By supplying power through pin 16 and a fused circuit (typically 7.5 Amp), these devices keep the vehicle’s computer systems energized while the main battery is disconnected and replaced.
However, it’s crucial to understand the limitations and precautions when using this method, especially on a 2011 Subaru Impreza. The 7.5 Amp fuse in the memory saver circuit is designed to protect the delicate electronics of your car. While the power draw of the various control modules in standby mode is minimal, activating any significant electrical component can easily overload this fuse. A common mistake is opening a door, which triggers interior lights and potentially other systems, drawing more current than the fuse can handle. If the current exceeds 7.5 Amps, the fuse will blow, effectively defeating the purpose of the memory saver and resulting in the same memory loss as if no power was maintained at all.
The consequence of blowing this fuse is usually just the loss of saved settings – radio presets and clock reset are the most immediately noticeable effects. In some cases, you might experience slightly rough engine idling for a short period after reconnecting the battery as the ECU relearns its optimal settings. It’s important to note that a blown memory saver fuse will not trigger the check engine light (CEL) or any diagnostic trouble codes. However, if the fuse is blown, it will prevent a code reader that relies on vehicle power from operating through the OBD2 port.
Therefore, when using the OBD2 port as a power source during a battery change on your 2011 Subaru Impreza, ensure that all electrical accessories are turned off and avoid opening doors or activating any systems that could draw significant current. If you are unsure or uncomfortable with this procedure, it is always best to consult a qualified automotive technician to ensure the process is carried out correctly and without risk of electrical issues. Using the OBD2 port correctly can save you the inconvenience of resetting your radio and other settings and help maintain the optimal performance of your 2011 Subaru Impreza after a battery replacement.
