Around November 2015 engine light came on, my sct scanner said was cylinder#5 glowplug, the shop said if the light didn't bother leave it alone because a lot of times the harness would be brittle and was not worth touching because being here in central Florida was so hot glow plugs do nothing for the engine, winter came and truck started and runned good, no issues. Last week driving home from work the light turned off by itself and hasn't come back on.
The shop told me could be a false contact or the bulb went out, when I open the ingnition switch the engine light comes on then off so the bulb is good. Does the ecm reset it self or have any one ever heard this condition before?

 

its is a computer.. self check... problem went away.. for now.


there are codes that stay ON till a person resets it.
some that can be temporary ... unless problem continues over a set amount of time.. or starts.


and depending on problem.. light may stay ON... or blink... blink is bad.


READ the Manual.. it will explain...

 

Some codes are set and cleared by a vehicles drive cycle. There are not many codes that this happens with.