PO463 Fuel Level Sensor High Voltage?

2003 OLDSMOBILE ALERO
195,258 MILES • 3.4L • AUTOMATIC
Avatar
RALPHPHIPPS22
  • MEMBER
  • 37 POSTS
I have a video of what my gas gauge is doing. I have tried a new harness and fuel level sending unit. The PCM had a short in it causing it not to function but now it does but shoots to full and then drops down to E after. I think it’s a defective part
Video (Click to enlarge)
Attached Media
Jul 9, 2026 at 1:31 AM
Advertisement
Avatar
STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
To me it looks like the gauge is bad or you have a open connection.

P0463 means the PCM is seeing the fuel-level-sensor signal voltage too high.

So this can be the PCM is bad because the signal goes through the PCM but we should run some tests first. Lets do a continuity test for the two wires that control the fuel gauge first. Here is a guide to help.

https://www.2carpros.com/articles/how-to-check-wiring/

Here are the wires to test. Check out the images (below). Let me know how it goes.
Images (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Jul 9, 2026 at 4:25 PM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
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.