I'm very mechanically inclined (older type cars). I've got a 03 CTS with 3.2 (base model). Runs fine with 50k miles.

I need to get my annual emissions testing done, and two days before I had it scheduled, the Check engine light comes on.....and has been on for these couple of days.

The shop says that I can not get the emissions testing done, with the light on (immediate fail regardless of the reason for the light).

I'm very cheap and I enjoy figuring things out on my own, so How do I get this light off? Do I need to buy a code reader? Will it re-set the light?

Help out a new guy here.

 

Autozone will read the code for free.
They usually won't turn off the light.
A code reader should be able to turn the light off. It may come right back ondepending on the type of problem your car has.

 

Thanks. I'm not really anywhere near an AutoZone. I've got Advance Auto and Pepboys nearby.

Either way, I wouldn't mind purchasing a code reader, as long as I know what kind is compatable with my CTS and can actually Clear out the codes to shut the light off. I've started to research different code readers, and it seems like they are between $30 and $150! What's the difference. Also, does my car have CAN (manditory in 2008).

Thanks for any help.

 

03 CTS did not use CAN. 04 or 05 was the first year.

Some code readers only read the codes.
Some also give you the sensor readings that the computer sees.
Some even allow you limited control over different systems.

 

So I guess a code scanner that gives me "readings": is better (probably cost more too).

So as long as I get a tool that reads all OBD2 protocols, I should be fine, but I don't NEED the ones that read CAN.

Question: The 04 and 05 CTS's use CAN, do you HAVE to have a scanner that reads CAN, or will a regular old scanner that reads all protocols for OBD2 be fine. I thought you only need a CAN starting in 2008?

If I'm going to make a purchase of a scanner, I'd like to get one that will be good on future car purchases if I can, and it's not too expensive.

 

You want a CAN scanner then. Most new cars have already switched over.
The computer (in car) and scanner have to use the same protocol in order to communicate.

 

Thanks!