Chevrolet Repair: ever hear of this? check engine question, plymouth acclaim, great shape

Question
92 plymouth acclaim automatic. great shape. took it for an oil change and inspection check up. i passed. while pulling out of the place the "check engine" light went on! thought this was strange as it is never on. figured it would go off. but has been on ever since, a week now. what could this be? have had car a few years and check engine light is never on. have oil changed and inspection and leave place with check engine light on!! it is a valvoline place and they don't do repairs, so i have not brought it back to ask them about it. thanks, rick

Answer
Hi Rick,

They either knocked a plug off of something, disconnected something for access to their work and for got to plug it in, or something is bad.

Here is the good news.  Your car will tell you much by checking the codes.  Here is what you do.  Put your key in the ignition and turn it on iike you are going to start the car.  Turn the key enough to turn on the radio and blower, but not the start it.  Do this three times fast.  On the third time leave the key on.  The check engine will be lit and will go out.  Then it will start blinking.  Count the blinks.  A short pause between blinking sequence is the two digit number, a long pause is a new number.  

So: 5 blinks - short pause 3 blinks, then a long pause, then 5 blinks and short pause and 7 blinks and long pause is a code 53 and 57.  Get those codes and write me again.  I will tell you what they are and what to do.  

C J S