FAILED SMOG TEST BECAUSE OF HIGH NO(PPM) IT MEAS 589, MAX ALLOWED IS 504

http://m.smogtips.com/failed-high-NO-nitrous-oxide.cfm

You can test it with a vacuum pump

I would be say if new spark plugs,new air
filter,new or clean rotor & cap,synthetic oil,don't take care
of it,you will need a new converter

Don't forget the oxygen sensor may be old as well

Clean out all leaves & dirt between the condenser
& radiator & make sure it doesn't over heat

The converter may be blocked as well as worn out

NOX is high coolant or engine temps
& egr issues

Lots on the internet to study on exhaust gases
& the reason they fail inspection or are too hi

Any codes? any problem tune up, catalytic convener, burning oil.

just had problems with two of my cars replaced the oxygen sensor. EGR valve and lastly the Catalytic converter the both cars passed with flying colors

run the fault codes to find the faulty sensor
sensors that control the exhaust emissions are the HO2S ( heated oxygen sensors in the exhaust manifold/s
the O2 sensor ( oxygen sensors after the cat converters ) and the EGR unit that recycles exhaust gas back through the engine to re-burn the gasses

High HC means moisture in the system. Try driving it longer then take it to the smog shop. Otherwise it could be hard like a head gasket or easy such as a PCV not functioning. Any ways you should always drive it about 20 miles before smog check, longer when the weather is cold.

most likely its the O,2 sensor

Things to consider or replace...

If you are getting a Check engine Light let me know, it will make things easier to diagnose.

Catalytic Converter
Oxygen Sensor
EGR Valve

You did not post the odometer reading on the van but base on the year it should has over 85,000+ miles on it.

The most likely source of the high Hydrocarbon (HC) is clogged or drippy injectors.

Change the fuel filter if it is over 48K miles.

Ran two or more tanks full of Chevron gas will help clean out the fuel system.

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The air fuel ratio can be off is the air filter is clogged or the mass air flow sensor give incorrect data to the computer (ECU).

Change the air filter is it over 20,000 miles or you can see sunlight though it.

Use CRC Mass Air Flow cleaner or electronic part clean to gently clean the mass air flow sensor.

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Change the oil to 20W50 or one grade higher to prevent blow by.

You current motor oil is soak with HC from blow by.

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Make sure the tires are at 32 psi

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Do the smog test is a COLD morning?

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REMOVE excess cargo off the van.

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These are little things that I would do.

If the HC is still high at 25 mph then you will need a professional fuel injector cleaning or replace the injectors.


Please post more data on the third smog test on the comment window.