Check engine light on idle only

Um yeah, if your antifreeze is low....you need to add it! I don't know if that will solve your check engine light issue though. If it gets too low it will shut your engine down...

 

Use the shut down over ride switch to get the flash code. Then Google that flash code. But yes, if low on antifreeze you will get the yellow check engine light.

 

Wow..... Who buys a truck and does not know how/or when to add the proper oil and anti freeze????

Of course you need to stop now at any truck stop across america.....call freightliner (or look) and see what is the proper anti freeze (green or red) fill it .... Purchase an extra gallon to keep just in case since you are really low..... Read an owners manual or talk to a mechanic or other o/o about proper oil to use.....I sincerely hope you will not damage your engine by not paying attention to detail

 

Put a voltmeter on the battery at idle, (probably better to the back of the alternator) and then with raised revs, see if it's putting out charging volts - just a thought to the light at idle . . .

 

Lol, that's a bit of a stretch seeing as he not quite sure what oil to put in it or to fill the rad.

 

If you're low on coolant you should get a CEL while driving. Does the CEL clear if you rev the engine while parked?

 

Light on at idle that goes away when you raise the rpm's could be low on coolant or it could be low oil pressure. If it happens only when the engine is warmed up it is probably the oil pressure.
When the engine is cold the oil is thicker. When warmed up the oil is thinner. Low oil pressure issues will be first noticed when engine is at operating temperature and engine is idling. When rpm's increase the oil pressure will increase.
Low oil pressure at idle is a sign the bearings in the engine are worn.