PO463 code

Hi all,

New to site. Just bought an 04 Aveo LS four door sedan. Picked up car with near empty tank ( No check engine light. Filled with gas, drove about 100 miles and check engine light comes on. Went to Auto Zone they put a scanner on it and up pops P0423 code ( Fuel Level Sensor A Circuit High Output ). Drove car about 125 miles total. Once fuel got to 1/2 tank on fuel guage check engine light went away. Does this sound like a bad fuel sending unit ? If so can you get to the sending unit under the back seat or do you need to drop the tank ?

Thanks in advance for any advice

Did it come back on later? If not I wouldn't even worry about it.

Yes filled tank again and CEL came back on.

I means the ecu is getting too high a voltage from the sending unit. You'll probably need to replace it (sending unit).

I would probably attempt replacing it in that case. It should be accessible through the floor under the seat?

Can anyone verify that I can access the sending unit from under the rear seat?

Replaced sending unit. Was able to get to fuel pump by pulling the bottom of the rear seat. 400 miles and exact same problem. Anybody have any other ideas?

The title of the thread says P0463, but the write-up says P0423. If it's the later, we're talking about a whole different animal. But if it is a P0463, you should take a careful look at the connector, and following the wiring for that sensor as far as you can go. If nothing turns up from that, you could try a new gas cap. Not saying it will solve the problem, but it's a fairly inexpensive and easy thing to try.

It is P0463. I will try your ideas.

Thanks

Happy to report back after a few tanks full of gas problem cleared itself ( I did nothing else). Fuel gauge works great. No check engine light. Fingers crossed.