more likely,,, the oil pressure sender, (or low oil) but anything is possible.
A complete model and serial number may help getting you better information.
You say you got a coded 115? this (if accurate) shows to be 'low engine lube oil pressure', [however, read on...]
?You are aware these truck's codes repeat 3 times, and then move to the next code,there should have been 'an alert' code that shows that it is flashing codes and this code is the first code of each set, so flashing 3 times a 166 code THEN flashing the 115 code 3 times then repeating back to 166 (etc...) would have been what I expected to see.