P0505 code question

1Salty Dawg

TJ Enthusiast
Supporting Member
Joined
Sep 14, 2021
Messages
149
Location
Jacksonville, FL
New guy here. My new to me 1999 TJ auto. 4.0 is throwing a P0505 code gas gauge reading empty when full and CEL on. Jeep runs fine, no hesitation, spitting or loss of power. Starts right up on first try every time. I took out the IAC valve which looked brand new and still cleaned it up any way but no change. Any one have any ideas? Thanks
 
New guy here. My new to me 1999 TJ auto. 4.0 is throwing a P0505 code gas gauge reading empty when full and CEL on. Jeep runs fine, no hesitation, spitting or loss of power. Starts right up on first try every time. I took out the IAC valve which looked brand new and still cleaned it up any way but no change. Any one have any ideas? Thanks
Did you clear the code by detaching the negative battery cable for about 10 minutes or using an OBD II Scanner?
 
So I disconnected battery for 10 mins and now the gas gauge reads over full and CEL still on. I had filled it up initially and drove about 50 miles when I bought it so I feel it should read just under full. I am going to check connections at the throttle body and see what happens.
 
So I am right back where I started my original post. Runs good, no RPM fluctuation etc. I feel there is nothing wrong with the IAC valve at all. Help.
 
Is the CEL, gas gauge reading empty and P0505 all related? I feel they are, I did the gauge test and all gauges seem to work with that. I took positive cable off for 10 mins and then start the Jeep and gauge goes to full. Turn off Jeep and restart and gauge reads empty. I checked where the wire harness at the fuel tank is and seems tight with no visible wire damage. The scan tool I have is generic at best so it says it is clearing the code but doesn't.
 
So replaced fuel pump with a Bosch and now the gas gauge goes right to full and still throwing a P505 code. The IAC looks brand new but I know that doesn't mean anything. Maybe that? What else can I look for? I checked the grounds, vacuum leaks, what else??
 
I borrowed a friends very cheap scan tool and I cleared the code once then it cam back and now won't clear and gas gauged pinned to full.
 
I haven’t had my tank down or replaced my pump yet, so this may be a dumb question. Can you reverse ground and fuel level wires?