First set of codes were 2 and 17, oxygen sensor, and speed sensor. The oxygen sensor was replaced but the speed sensor wasn't. So theoretically I would still get a CEL, no? The thing that concerns me is the engine idles rougher once the CEL comes on. Mechanic said it was motor mounts, compression test came back good after a different mechanic said I was running on 2 cylinders. Any suggestions?

91 Accord EX 225k.