Yeah, as soon as a factory bulb went in it worked immediately.
Thanks for the hint! I looked into this some more, and I just realized that I'm an idiot. I thought 168, 194, and 2825 bulbs were all the same. Well, they're not despite looking the same. I compared the wattages of those 3 bulb types and also 3 different Sylvania offerings for each type:
Bulb Type | Sylvania Basic | Sylvania Long Life | Sylvania SilverStar |
168 | 14V, 4.9W | 14V, 4.9W | 14V, 4.9W |
194 | 14V, 3.8W | 14V, 3.8W | 14V, 3.8W |
2825 | 13.5V, 5W | 12V, 5W | 13.5V, 5W |
The bulbs I used were Bosch Bright White 194 (12V, 3W) bulbs. I just put in a pair of Sylvania Long Life 2825 bulbs, and the error code is gone. I'll update if it comes back, but I think I've solved it with you all's help.