 FYI: CAI/MAF engine code info you might need
When my JLT was "adjusted" after I first installed it a while back (before FI) I somehow neglected to get the MAF re-attached firmly before closing the hood and starting the engine, which of course threw an "engine wrench" code that put the car in "limp mode" while it was running.
The "code"/instrument panel light wouldn't disappear while the car was running even when I opened the hood and "re-attached" the MAF harness properly. Instead, it was only after I had done the re-attachment and turned off the engine/re-started the vehicle that the instrument light cleared.
So the lesson is if you either don't get the MAF harness re-attached at all or properly (i.e., to lock the connection in place) you'll "get the wrench" light and be able to clear it like I did. | 
