Cadillac: 1991 Cadillac Sedan Deville (4.9), cadillac sedan deville, full tank

Question
Can you please help?  My mom has a 1991 Cadillac Sedan Deville (4.9) she is having problems with.  She recently got a full tank of gas (she was on 1/4 tank), shortly after the car's check engine light came on and the car started to stall out.  My husband first thought it was the catalytic converter, but it acted the same (loading up/running rough) when the exhaust system disconnected.  He changed the spark plugs (which were extremely worn) and the fuel filter (which was semi-restricted).  The problem seems to be diminishing, yet when test driving it will occasionally stall.  He did a code check and the read out was E31, E73, E74.  Do you have any suggestions?

Answer
E31 = Shorted MAP sensor circuit.

E73 = Intermittent coolant sensor.

E74 = Intermittent MAT sensor.

Did these codes show up as ONLY E codes or were they or some of them EE codes ?.


Sounds like you got a load of water with your gas. Put some DRY GAS or similar product in the gas tank to clear out the water.


Also CLEAR (erase the codes from the computer and see if any come back.