An alarm is sounding in the Oldest House's lowest sections for the first time in decades, and Dylan should find out what is wrong. Maintenance Protocol is a puzzle-heavy side quest across the Underpass: investigate the alarm, track down three unusual light bulbs, fix each one in its own way, and then deal with what waits in the projector room.
How to Start
The quest starts automatically when speaking with Zoe during the Zoe's Briefing side mission. The only requirement is having completed Zoe's Briefing. Once it is in the log, head for the Underpass.
Walkthrough
1. Investigate the Oldest House Alarm
Travel to the Underpass region, near the Deepest Underpass fast travel door. Look south for a climbable ledge with a door leading into the Oldest House. Inspect the door to speak with Zoe, then use the keypad to the left of the door to get inside. Defeat the Mold enemies in the first room, then go through the south door. Follow the path upward to the projector room and wait for the video to finish playing.
2. Find the Light Bulb Coordinates
Use the console in the nearby room by the three red lights. This marks the locations of three bulbs scattered around the Underpass, giving the next three objectives.
3. Fix the Electrosensitive Bulb
The Electrosensitive bulb is directly below the Research Stations fast travel door. It needs its charges moved away from the three cores beside it: carry one charge to the core below on the northwest side of the platform, a second to the core below off the west edge, and the third to the core just past the second one on the same level. With the charges relocated, interact with the bulb to fix it.
4. Fix the Volatile Bulb
The Volatile bulb sits east of the Halfway Trail fast travel door. Interact with it once, then talk to it to calm it down — choose "You're okay." Hiss spawn after the first interaction, so defeat them while responding with "I'll keep them away from you." Once the Hiss are down, interact with the bulb again and pick "You deserve to be fixed," then walk up to it and interact one last time to complete the fix.
5. Fix the Botanophobic Bulb
The Botanophobic bulb is on the island north of the Research Site areas — follow the path north from "Research Site" and the bulb is mid-island. Destroy the Mold covering it to reveal the bulb, then interact with it to fix it.
6. Complete the Final Step at the Projector Room
Fast travel back to the Deepest Underpass fast travel door and return to the projector room.
7. Fix the Final Light Bulb
Interact with the light bulb in the video itself.
8. Escape the Slides
Dylan ends up stuck inside the video projection. Work through the dialogue to get out — select "Where are you going?", then "Unstable bulb", then "Do you know a way out?", and finally "Break the bulb." That completes the mission.
Rewards
Maintenance Protocol rewards the Standard Issue Coverall. No trophy is attached to this quest, but it is a solid chunk of Underpass content on the way through the zone's side offerings.
