Check engine light permanently on

rustygastank

rustygastank

TJ Enthusiast
Joined
Jun 11, 2021
Messages
160
Location
San Diego, CA.
CEL is on and it won’t go away;
Fixed the issue. Cleared the code with a scanner, light instantly came on when I started up the Jeep.

Disconnected the battery, cycled the ignition, let it sit for 10 minutes with the battery disconnected, light instantly came one when started up the Jeep.

When I say instantly, I mean it’s not as though it’s idling then the light turns back on, I mean it never is shut off when the Jeep is running

Any thoughts
 
I wonder if it was the purge valve and/or cannister ? if I remember correctly mine wouldn't reset until i filled it up and drove it through a tank of gas !
 
  • Like
Reactions: Gollywomper
0433 purge valve evap system. I've just never had a CEL stay on regardless of clearing or pulling the battery.
I forgot to check fuse 11 but really just curious why the computer wont even run through a cycle before telling the CEL to turn on.
 
Just FYI you can't clear codes with the engine running. Ignition needs to be in the run position with the engine off.
 
rustygastank said:
0433 purge valve evap system. I've just never had a CEL stay on regardless of clearing or pulling the battery.
I forgot to check fuse 11 but really just curious why the computer wont even run through a cycle before telling the CEL to turn on.
Click to expand...
Check all the lines running to the purge valve. Specifically the rubber passing through the engine bay. Mine where cracked from the heat coming off the cats.
 
It is possible to have a fault in the instrument cluster, my current 99 had a constant CEL without codes and replacing the cluster solved the problem.
 
I'm not as familiar with the TJ system since it's never given me problems, but I've had vehicles that run a leak check when the vehicle is off, so it doesn't have to have run for any length of time to trigger the fault. It's already there as soon as you start it up.
 
Top Bottom
Back