http://www.obd-codes.com/p0442
P0440 indicates the failure of the EVAP system to develop proper vacuum. If you got
and replaced a proper good quality gas cap, you have corrected the most common cause.
However, in fully searching the causes of this code (http://engine-codes.com/p0440_chevrolet.html ) (pardon the generic GM info, but will apply for you)-----you will find there are 5 other causes of the vacuum failure, which are independent of the gas cap. Your good local mechanic can sort those out; I would save your gas cap
receipt if you were advised to buy one not needed. As you probably know, your
State emission test facility checks your gas cap----so that is another way to find that specific portion of this answer,
(for their fee).
P0300 is a generic misfire code. For this, a specific Cadillac forum may be most
helpful =
2001 Deville intermittent service engine soon light code P0300
2001 Deville intermittent service engine soon light code...
I recently bought this car from an owner who took decent care of it but a week after i bought it, the service engine light appeared. After a few
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You will see that this generic code is perhaps more serious, costly, and harder
to track down than the P0440. You will also discover that P0301 is cylinder 1 misfire, P0302 is cylinder 2, and etc, etc. If you get a good diagnostic, they will generally
be able to localize the problem fairly specifically---and get a more specific fix. The person who reported this code was unhappy because he was given several ($$) fixes,
before he got one that erased the code, and was a solution. (Be forewarned ----A generic misfire can have umpteen issues--or one! !; use your own local preferred method for solving this with a mechanic who gives you good service, and stands behind what they do.)
2001 Deville intermittent service engine soon light code P0300
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