I guess your cat/s needs to be changed. Co is high due to a rich A/F mixturewhich is a compensation for a lean running conditions. Like a vacuum leak, bad o2 sensor, or a bad cat that will trigger the engine light on. High nox is due to a hot running conditions because of lean or rich air fuel ratio, bad thermostat, and sometimes bad coolant temp sensor.
Many things to look at, just make sure before you swap anypart that you have a code that will help point you in the right direction
Depends on which of the readings failed. Was it CO (carbon monoxide), HC (hydrocarbons), NOx (nitrous of oxides), or a combination of them?
High CO levels can increase the formation of nitrogen oxides (NOx) through reactions with nitrogen in the atmosphere. This leads to increased NOx levels in the air. However, if CO concentrations are high enough, the combustion process in engines can be inefficient, leading to incomplete combustion and higher CO emissions.
High CO is a rich air/fuel mixture. Nothing else.
High HC is unburnt fuel. Check the O2 sensors, Plugs, wires,cap ,rotor, timing. If it failed CO & Nox also check the converter. Possible that it may not have been properly warmed up before testing. I would recommend looking at the o2 sensor (you only have one on your car) and the coolant temp sensor.
Add more hydrogen
CO, CO2, NOx, SOx
It depends on what is causing the high Co. It could be anything from dirty engine oil to and O2 censor. You need to find out what it is and fix it.
O2, CO2, NOx, HC, CO, H2O
i would like to know the answer, as I'm buying a 93 Lexus that has failed on the NOX ANY IDEA?......
They are not removed. They are converted from CO and NOx to CO2 and N2.
HC hydrocarbons CO carbon monoxide NOx oxides of nitrogen
Hydro carbons, oxides of nitrogen and carbon monoxide. HC, NOx, and CO