04 f150 heritage with inop cel. I have no owners manual and cant locate obdII fuse. I removed gauge cluster checked connections, checked all the mini fuses. After not driving the truck for a couple of days when I turned the ignition on the cel was on. The cel remained on until I turned the truck off. when I restarted the truck the cel was inop again. There are currently to codes in the system p0171 andp0174 lean banks 1and 2. So I know that the light should be on, also when I turn the key on the cel doesnt light up. Please advise thanks.

 

The OBD2 gets its power from the cig lighter fuse. If it were blown, the code reader wouldn't work.

Lean both banks is usually a vacuum leak - most often the PCV elbow behind the intake.

 

Thanks for the info, I got the fuse and a rotten hose replaced.