after failing the smog check for cat and evap, the smog guy said i just have to drive it, so i did.
i've also bought a scanner after driving for miles. cat and evap is fine. the hcat = heated catalyst shows up as n/a
from what i've read that most scanner with n/a is not applicable to the car i'm scanning...is that correct?

 

Evap readyness monitor is not required for California smog check. We need more info on the other one. What code are you getting? Is you CEL on?

 

no check engine light is on. I could just do the drive cycle but curious whats this hcat is about

 

O2 sensor heater circuit. It's a resistive coil built into the O2 sensor designed to heat the sensor and bring it up to operation temperature faster. It can and does fail sometimes. The question is which of the 4 O2 sensors is bad. No way of knowing without codes and just driving it a bunch won't fix the problem.

 

so the w211 have it? I'm not getting a check engine light for it...

 

No heated cat in your car, as indicated by the N/A listing. O2 sensors are heated, but if an o2 heater was burnt out you would get a check engine light quickly (simple resistance test). Any time you clear engine codes you also reset the "readiness" monitors. Drive it. Fastest way I've found to "ready" the monitors is to drive between 2000 and 2500 rpms at steady throttle position. Evap takes a longer time to ready because it does checks warm and cold. Not sure about your area, but here in Vt. you are allowed 1 monitor in a "not ready" condition

 

You need to get CEL fixed and to start you have to read the codes and post the numbers here.
heated catalyst for me would be DEF fluid, but does your vehicle has it?