I have a 1994 s10 blazer 4x4 with the vortec engine. A couple weeks ago I replaced my old exhaust and original catalytic converter. I got a magnaflow direct fit cat and the dynomax catback system. Everything went on fine and and I was very pleased, but last week the check engine light came on for about 10 seconds going up this hill and then went out again. Now it's doing it more frequently but always for a short period of time. I checked the code and it's a code 13. Something to do with an o2 sensor. I looked all over the forums about the dynomax catback and read that it shouldn't cause any codes to come on, so I'm a little confused.
My questions are,
1. Did my replacing the exhaust cause this problem, or is it a huge coincidence?
2. What usually causes a code 13 and how do I fix it? (I know its an o2 sensor issue but not sure about the specifics of what causes one to fail).
3. How do I figure out which o2 sensor to replace?

Thanks guys,
Melissa

 

I believe theres an 02 sensor AFTER the catalytic converter. This is probably the one throwing the code, there may not be anything wrong with it, it's just the fact that with the magnaflow hi-flow cat the sensor is reading as though it's running with abnormal emissions.

Im sure that's your problem, someone else can either shoot me down or confirm, I heard about getting the code deleted but don't know if that'd affect both 02 sensors.

 

I had the same problom on my 99. IT was caused by the high flow cat. Like oktain said the sensor was reading abnormal emissions, causing it to throw a code.

 

Thanks for your responses. But I don't remember seeing an oxygen sensor when I changed out the old exhaust for the new one. Are you guys sure if the first gen blazers had one there?