O2, EGR and Catalyst Sensors won't clear

[davidgjason]

2 years ago, my 96 240SX had an engine light for the speed sensor. Replaced the speed sensor, but the error kept occurring. Took it to a dealership (which I hate to do) and they said the "computer head" was bad. I paid nearly $500 to get that replaced and the error went away. Now, I can't get the car to pass Tx state vehicle inspection. The o2, catalyst and egr sensors are not resetting, even after 200 miles.Any ideas what I can check before going back to the dealership?

[Q45tech]

EGR passages dirty when were they last cleaned? O2 sensor/s sluggish when was it last changed? Cats depends on which codes.11 year old cars need maintenance.