What do i do for a code p1633?

2008 MERCURY GRAND MARQUIS
191,700 MILES • 4.6L • V8 • 2WD • AUTOMATIC
Avatar
NIGHTBLADE53142
  • MEMBER
  • 2 POSTS
Engine light came on one day so i checked the code but i am unsure what i need to do about it. Any advice or help would be appreciated.
Jun 25, 2025 at 6:49 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
Advertisement
Avatar
STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 54,178 POSTS
Yep, this means the voltage in the system is too low, when the engine is running do you have a battery warning light on? If so the alternator might be to blame as it is not charging.

P1633 - Keep Alive Power (KAP) Voltage Too Low

You can use this guide to confirm the alternator is working okay and if so, I would replace the battery.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please go over this guide and get back to us.
Jun 25, 2025 at 12:18 PM
Advertisement
Avatar
NIGHTBLADE53142
  • MEMBER
  • 2 POSTS
Battery light would come on once in a blue moon but when i tested my battery and alternator the tester said they were good, but the battery is starting to get old so i could try replacing that.
Jun 25, 2025 at 4:50 PM
Avatar
STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 54,178 POSTS
Okay, also, check all fuses int he under hood fuse panel, you might have one that is out.

This guide can help:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Please go over this guide and get back to us. Check out the images (below).
Image (Click to enlarge)
Attached Media
Jun 25, 2025 at 6:47 PM