What causes the service engine soon light to come on?

 

Generally it means you have a problem...Pull your codes and see what comes up...

 

It's a built in feature on C4's ; put there by GM to keep owners brains active and their wallets empty ..

 

Scott, run a search here on "how to pull a code on a 1995". Its quite simple. The code is telling you that one or more of your sensors is reading something thats either too high or low of normal.

 

I went to O'reilly's parts and picked up a simple GM only code reader for $29. No one around here had "just" the OBD I readers that gives you everything. You still have to read the blinks on the DIC but I got a 12, which the manual says is normal and is the system test, then I got a 13 which was the O2 sensors. Bought 2 and was gonna replace them myself but took it to the shop because the pax side one wouldn't come out. The muffler shop actually had to put in another O2 port for that one. After that...no more light and no more rough idling. The light used to appear about 10 minutes into driving. I know you can do this with a paperclip but the "gadget" is all enclosed and handy as well as the book with all the codes.

 

Thanks guys

 

1995's loved to eat up the 02 sensors. check the sensors on the left bank first. My 1995 coupe would foul one out about every 8 or 9 months. For a cheap fix try (if they are clogged) using electric parts cleaner that you can pick up at autozone to clean it off. Let it dry and then test it out. Might work for ya.