95 Caravan Check Engine Light

The first two digits are a code 12 which means start of codes. The last two digits are a 55, which means end of codes. The middle two are your problem and this is a code 21. I believe this is identifying an oxygen sensor problem. Do a Google search on this code using some keywords like "Chrysler Engine Diagnostic Code 21" and you will likely find a lot of useful information. Here is one page I found right away that provides some info for you on codes and proper procedure (on-ff three times not 5):

Bob,

Thanks, it has been running rich.

BTW, What kind of spark plugs would you put in there?

Bosch or A/C Delco?

Mike

Champion are the recommended original equipment and seem to be best based on negative feedback on the other two choices you named.

Bob

Crap, I just came back from installing the front 3. I bought Delco. Yes, the ones I removed were champion. I had to choose between Bosch and Delco. The guys in the shop recommended Delco.

I was under the car looking at the back 3. I didn't have time to install them though.

Do you think changing them from below is the easiest method?

Looks like I'll have to get a long screwdriver to push the plug cap off.

Mike

Mine (95 3.0 Ltr) came with NGK's installed. Not being a fan of AC or Champion, I have always replaced with same.

Much easier (IMHO) to remove the air box on top and get them from the top-side. #1 can be a pain in the A$$ due to the alternator bracket, but can be gotten without removing bracket if you have a knuckle attachment for your ratchet.

As I recall, I accessed two of the rear plugs from underneath the vehicle and removed the rear alternator bracket and accessed the worst plug (passenger side rear) from the top side. Note that I did not need to remove the alternator and it did not move since it was secured by a front-side bolt.

With regard to the plugs, NGK are an excellent brand and were used as original equipment with the Mitsubishi 3.0 engine. As I recall the OP had a Chrysler 3.3 or 3.8L and these came with and work best (in my opinion) with Champion.

Bob

NGK's are the best. NExt time.

BTW, reading back up at the original post about my "Check Engine Light". I replaced the O2 sensor and the light does not seem to go on anymore. Not on in either 2 times it has been driven.

How long before the codes get changed back to the default?

Is 1,2,5,5 the default?

Thanks,

Mike

This should return back to 5,5 after I believe 20 starts.