(Posting here since this section gets more traffic than the truck section)

Took my Dakota in for its annual smog test, and it failed the Low Speed NOx.

Am I wrong to think that if it was the catalytic convertor more readings would be out of spec?

I'm leaning towards the EGR, but that's just a guess. When I had the intake off (last year), I cleaned the EGR and the port out as much as possible, but, did not test or replace the EGR.

Plugs, cap, coil were all replaced spring of 2015.

Truck other wise runs fine.

Here's the link to the test results: Results



Oh, this is my '93 Dakota with 3.9 and 168K miles...

Suggestions?

Thanks.