I have a 2011 Legacy Sedan with 40K miles. Three weeks ago, I drove the car 25 miles in 90+degree heat on the highway. I parked at a store, did not use the electronic parking brake and when I returned to the car 5 minutes later and started it, the dashboard BRAKE light was flashing. The brake was not engaged. I tried to engage and release it, but it would not engage, when I pushed the button the car 'chirped'.
I drove the car home and garaged it. The next morning (after a cooler evening) the light no longer flashed. At that time I was able to engage and release the electronic parking brake and it worked as designed. A similar sequence has occurred on four different occasions. When I start a cool car, no light. When I start the car after it's been run for a while in 90+ degree heat, I'm getting the light flashing. I've checked the brake fluid and it's fine. I've checked the OBD and it shows no codes. For what it's worth, I rarely use the Electric Parking Brake. Any thoughts on what to try next?