Catalytic converter monitor will not let me smog car inspite of 1month driving and 700 miles on car

limited info generic answer the cat is usually the last and driving 2 hrs is not going to do it and usually need to do quick drive cycle 2 or 3 times -----or over 125 miles of alternate driving --https://smogcheckvacaville.com/general-motors-drive-cycle-for-smog-check/ ----------- https://repairpal.com/how-to-perform-a-basic-drive-cycle ---------

Make sure it has the correct thermostat temperature, 3/4 tank of fuel. After it reaches operating temp, drive at 55mp for at least 5 min. 99% of the time this will do it. Good luck

I expect the CAT isn't lighting up. After a relatively short time of normal driving the closed loop fuel control should produce the ideal conditions to promote the chemical process in the CAT that causes a sudden rise in temperature that begins the conversion process of reducing the harmful and polluting content of the exhaust gas and that is monitored by the post-CAT oxygen sensor.

The electronic brain needs to "see" that reduction in harmful emissions when compared to the pre-CAT oxygen sensor and when it does it should be ready for test.

I expect the CAT isn't working and while they don't last forever, their ruin can be hastened by all sorts of things from mechanical impact or being quenched in cold water (deep puddles), an oil burning engine, too much fuel, a leaky head gasket or merely old and tired sensors.
Your car has reached the sort of age when the overhaul should begin with a fuel pressure test and a fuel injector test...

Not sure how old the vehicle is, or model, or engine, so I can only give general suggestions. You may need new catyitic converters, or O2 sensors. They sometimes can't be corrected, just replaced.

Well, the actual procedure is to drive the van far enough to let the engine computer sample a wide range of conditions. The standard method is 100 miles at various speeds including highway and city driving. You could do it in 30 or 50 mile runs but it needs to be over 50 miles total.

Sometimes it CAN take up to 500 miles!

In order to set the monitor it the drive cycle 2 trip criteria that means you need to have a cold start up and reach operating temperature then another cold start up with a operating temperature reached and the drive for each one is part throttle hold for 2 miles and a decelration for the catalytic to get ready.when the cat is ready the evap runs.If you are loosing monitor at key off and everything reset you can see the referee let them smog it. The EGR and EVAP are almost impossilbe to get ready

The P0420 is for the catalyric converter, you'll have to have it replaced. It will fail the test as long as the light is on. Clearing the code information also clears the monitor infor, to pass the monitors required you'll have to put some miles on it in both city and highway driving, not all monitors may be required so check with your local smog station which ones have to pass.

Follow this drive cycle to reset the monitor.

http://www.obdii.com/drivecycleford.html

Drive the car for 2 miles non-stop and take it to smog inspection WITH OUT TURNING OFF THE CAR!! the key is that the car goes threw the test while the engine is running ...

if the car is turned off ... u will have to repeat procedure ...