Just went out to start my 90' DeVille with a 4.5L engine and I heard a thumping soundwhen I turned the ignition to on. The engine started OK, but the "service engine soon " light came on with trouble codes 22 (open TPS circuit) and 38 (open MAT sensor circuit). The car was running fine the last time I used it one week ago.
What could have caused this to happen all of a sudden?
Can the cold temperature cause these sensors to malfunction?
Are they entirely electrical in operation or are there mechanical or vacuum components?
Should I replace either one or both or see if the connections might not be good?
How easy or difficult is it to get to these components to check them or replace them?
How expensive are they?
Any advice would be greatly appreciated