I think s/he means oil level sensor.I have to say I've never heard of a 'check engine' light SENSOR.
I guess you could say that nearly every sensor on the truck is a "check engine light sensor" You need to have someone "pull the codes" and repost here with what they are and we may be able to help. Good LuckI have ML320 year 2000. I need to replace check engine light SENSOR. Any help I can find here.