My truck keeps tripping a P0237 code for the MAP sensor voltage too low. Ive gone through 2 new MAP sensors and it still does it, ive checked the wiring, nothing looks damaged. However, this is where it gets wierd, if i clear the code, start the truck, I can drive it all day long without the code coming back, provided i dont shut the truck off, if i shut it off and leave it sit for over 30 minutes, the code comes back as soon as i turn the key, however, if i start the truck before 30 minutes have passed, it doesnot come on. any thoughts,

PS: Box has been unhooked and removed entirely from truck with no change in symptoms

 

Well since no other theory holds any water in my opinion at the moment, I am gonna say you may be experiencing the early stages of an ECM failure.

 

Sounds like an ECM issue.

 

Ensure that battery voltage is good before starting, and after. There is no good reason that only the MAP sensor would throw that code, but it is something quick and easy to check. Not sure if everyone knows, but 3 wire sensors use a 5V signal, not 12V. Therefor having one 5V sensor bad and not all of them throwing codes it seems a little odd. Double check grounds as well, they can cause all sorts of trouble. The last thing to check would be the pins in the connectors themselves. I have found a few in Heavy Equipment that are loose, not crimped properly, or corroded that can cause problems.