Check Engine Light (2005 Liberty)

The Check Engine light came on about a 6 weeks ago with a 305 code. I
brought it to the mechanic who played with it for a while and the light
went out, apparently satisfied.

Three weeks ago it came on again, same code.

I had to wait a while to bring the truck back in and during that time it
sat for two days without being driven. When I drove it again the light
was out, yet came on a couple days later, same code. A week or so goes
by, I fill the gas tank and when I started the truck the light was out
and stayed out for a couple of days. It's on again now.

I'm wondering why filling the gas tank or letting it sit for two days
has to do with the problem. If the truck is misfiring on the 5th
cylinder wouldn't the light just stay on until the problem was fixed?

J

 

A loose or bad gas cap will turn the light on.

 

A loose or bad gas cap will turn the light on.
But it won't set a code P0305.

 

if i read it right that would be a p0305 misfire code code meanig
cylinder#5 is having issues could be fouled plug or failed coil pac bad
injector /bad injector wire,connector and if those check out good a full
engine compression test would be in order to see if low compression is the
root casue of that code setting when was the last time you had a full
tune-up??? if you are do for one do not use bosch spark plugs they fail at
a alarming rate