Hey there,

I just had my mechanic install a brand new magnaflow catalytic converter on my 04 1500 hemi. When I got the truck home I checked the new cat with my infrared thermometer. From what I understand the temp should be roughly 20 degrees hotter coming out of the cat, but mine is a whopping 250 degrees hotter going in.

So my question is, does the cat need a break in or something? Or is something wrong?

Thanks

What's the temp at the front of the cat? Generally, they don't really light off until above 350 degrees.

Front of the cat was over 500. Rear was in the 200's

Something is seriously awry there then..... that's hot enough for the cat to be doing its thing. Sounds like it is either empty, or plugged....

I just thought on something. You said empty and I read that a new cat needs a break in. From what I read the inner part expands once broken in. Is it possible that it hasnt expanded yet and the exhaust is just going around it rather than through it?

Thanks

I believe you are indeed correct. Put some miles on it, and test it again in a few weeks.