Hi
I just had my emissions / smog check here in California for my 1987 Mercedes
300E and the NOx were really high. Very close to failing.I suspect a bad cat. I measure the temp of the cat with a fluke infrared and measured 245C or 473F. The temperature was the same at the front, middle and back of the cat. The car was running at operating temp, I did this after I came home from work and the water temp was near 100C
Shouldn't the reading be closer to 426C or 800F?
Ideas? It looks like the original cat , the car has 175,000 miles