I have a 07 Thomas freightliner with a Mercedes 906, the oil pressure goes from 50 to 100 and the tach drops to zero then the check engine cones on. I don`t have the equipment to read the codes but was wandering if anyone has had this happen also. thank for listing.
Never worked on a Thomas Mercedes engine, but have you tried replacing the oil pressure sensor? The tach dropping to zero wouldn't make the engine light come on.
I also forgot the foot feet wouldn`t work when the check engine light was on. It was cold and windy yesterday bus temp was 150 and I heard the fan kick on, Will it store the codes so I can have a shop read them. No haven`t tried oil pressure sensor yet. and thank you