Strange cause and repair for PO401 code
Strange cause and repair for PO401 code
97 F150 with 4.6. Had a EGR flow code PO401 and thought i had it fixed. It came back when the monitors reset. Worked on it today and found the strangest cause that I have seen. Could not get vaccum to the vaccum solinoid for the EGR valve. When tracing down the vaccum reservoir I found the bundle of vaccum tubes that are at the bottom of the battery box had acid on the loom holding them. Removed the cover from the battery and found the negative post leaking acid. Pulled battery and inspected the loom and found the vaccum hoses in it were eaten up with the acid. Repaired the vaccum hoses, moved the bundle and reset codes. All monitors on and no codes came back. Thought this might be useful to the F150 owners.


