sensor Help

What are the sensors on the rear of the block below the head... i have the temp sensor but there is another spot for one... i cant find it in the haynes. The one on the right when looking at the back of the block (below the intake manie) we have we need the one on the left and slightly higher... PLEASE HELP

4 cly... thank you


Nick

Be more specific, Also if you can get a pic and I might be able to help:)