I have a 1992 240 Sedan. It has about 162k on it. It runs pretty well, I did the plugs, wires, cap, rotor about 6 months ago. A couple years ago it would get 30mpg on the highway, and now it's more like 27.

So I stupidly assumed that I'd have no problems w/the test...I took the car out on the freeway for 20 minutes and then went to the place around the corner, not realizing that they don't retest for free if you fail...

So I wasted $40.

I failed the NOx, and he said my Thermostatic Air Cleaner hose was missing.

I don't think I've ever had a hose on there before...
is it vital? Will it be beneficial?

My HC and CO were both well below the max, but def. above the average.

My NOx at 15mph was 797, allowable is 791
My NOx at 25mph was 373, allowable is 730

This seemed odd to me.

My car is a '92, so I don't think I can try the Chrysler ignition trick...
Probably a new cat? I've had the car for 4 years, and have no idea when it was last replaced.

Any other suggestions?

Thanks all.