Co levels too high - 1993 Honda Prelude

CO? That means Carbon Monoxide - it's a rather toxic and poisonous gas emitted from the exhaust system.

When they check emissions on cars CO is one of the gases they measure. If the level is too high .. your car fails the emissions test. I believe in the USA the emissions test is known as the 'smog test'?

If you have a problem with excess CO emissions on a car the cause is often an incorrect fuel/air mixture or a faulty sensor called the lambda/oxygen sensor in the exhaust system

We're these at idle readings ? What were the off idle and cruise readings, if available ?

have your air/fuel (a/f) ratio checked. high CO level means you have a rich a/f mixture.

rich a/f mixture means there is too much fuel compared to air. this is bad for fuel economy.
lean a/f mixture means there is too much air compared to fuel. this needs immediate attention since this might lead to over compression in the combustion chamber, which develops to total internal engine failure.

possible bad thermostat

change the level of octane to a higher grade before you get your car retested.

High CO results from a vehicle running 'naturally' rich - ie a rich condition that is not being forced from the computer.

The basic, most probable causes of a high CO count could be one of the following;

High fuel pressure (constricted filter, pinched line, etc)
Ruptured pressure regulator diaphragm
Malfunctioning Evaporative Emissions System
Crankcase fuel contamination (head gaskets, injector/regulator leak)
Closed loop incorrectly shifted to rich (o2 sensor, map/maf sensor, coolant temp sensor, Throttle position sensor, etc, etc)

Tell me...What is the NoX Reading?

you need to run a specific cleaner in your gas, it cleans the cat, also it is called HT-1 and is made by MALCO PRODUCTS it runs about $45

Not sure, but did you replace the oxygen sensors. Is your catalytic converter still good?

Check vvt servo motor

check out lamba sensors ,ask a local garage to plug car in and check voltages ?