DON'T LET YOUR VOLVO GO TO THE SCRAP YARD!

Since 1975, California has led the way in making cars emit fewer pollutants.While this is good for the environment, good for people and basically good for all living things, it does create a few other problems. One of them being that if your car can't pass the bi-annual test, then your ability to legally operate it on California roads is gone.Some are willing to spend the money needed to have their car professionally repaired so that it does pass. Others may see the repair estimate and simply send the car to the scrap pile. An example of this would be Volvo cars with the "white block" engine from the late 1990's. A common point of failure are the coil harnesses. The insulation can deteriorate causing the wire to ground out. The car still runs, but a CEL light is set and unless this gets fixed and the light is cleared. it can't pass smog. Getting this resolved is technically easy, but the parts from Volvo can cost thousands. So the car gets scrapped.

(Thanks to reddit user turbo_charged)

I’ve been getting 240s through CA smog for 10+ years now.

NoX is generated when combustion chamber temps are high or when the vehicle is under heavy load. Lean running conditions raise combustion chamber temps.

Several things need to be working well on a 240 to avoid high NoX while smogging:

-No vacuum leaks on the intake side. Check your hoses, rubber elbows, intake tube, throttle body gasket and intake manifold gasket.

-If your 240 is a 50-state car (I.E. California), it has an EGR valve and this system HAS to work. There’s an electric solenoid near the ignition coil that makes a rapid clicking sound as soon as the throttle is opened. 

-If you remove the two vacuum hoses at this solenoid and connect them while the engine is idling, the RPMs should drop and it should begin running rougher. If nothing changes this means the EGR valve is  not OK.

-The O2 sensor should be in good condition, and sweeping between 0-1v briskly with the engine running and fully warmed.

-Exhaust leaks between the engine and catalytic converter will introduce fresh air into the exhaust system, which will make the O2 sensor report a false lean condition AND make the catalytic converter unable to effectively reduce NoX. Exhaust leaks past the cat will have no effect on emissions.

-In the air filter box, there’s a flap at the bottom controlled by a wax thermostat to draw in heated air during extreme cold starts (I think it opens at 40 degrees F or lower?). These wax thermostats fail in a position that draws in heated exhaust air constantly, which raises combustion chamber temps and will eventually ruin the MAF sensor. Replace this wax thermostat or block off the heated air inlet to lower combustion chamber temps.

-If the aforementioned flap has been in the heated air position for a long time, there’s a very good chance the MAF sensor is ruined. A dead MAF sensor can cause high emissions. 

-If the engine is running too hot, NoX will increase. The fan clutch should be working. 

EDIT: 

To that effect, make sure homie running the smog test sets up that big fan you see in front of the car (which appears to NOT be running during your smog). He’s supposed to turn that sucker on full blast and point it at your radiator when he’s running the test—it gets very hot in that tiny space and that fan makes a huge difference in temperature.

-Poor/inadequate fueling will create a lean running condition which will increase NoX. Both fuel pumps should be working, the fuel filter shouldn’t be clogged and the fuel pressure regulator needs to be working.

EDIT: 

-ECT being wonky could cause this, but it sounds like you’re able to drive it freeway speeds at speed without any trouble so sorta I doubt it. Good drivability is a good sign for smog.

-Blown head gasket will cause high emissions. 

My own 240’s head gasket failed because the gasket just corroded away. My car was infamous for passing smog within 3 PPM of the NoX threshold multiple years in a row. One day I started it and the exhaust smelled exactly like coolant, and that’s when I discovered the HG failure. It never once overheated. It had 236k and been in service 33 years at that point—it was just old. After replacing it and cleaning everything, it passed smog cleaner than any of my pre-OBD smog-required Volvos. 

-Your emissions printout will tell a story that will help solve this. All of the measured numbers together will be very helpful to know.

Before going to see the smog man:

-Do an oil change. This mostly helps HC and CO but fresh oil responds better to heat and isn’t full of raw or partially burnt fuel.

-Increase rear tire pressures to the maximum PSI listed on the TIRE, not the door. Correct the tire pressure after your smog is complete. This reduces rolling resistance which reduces engine load.

-Drive it aggressively for 30+ minutes (high load and high RPMS) immediately before smogging, and leave the engine running while you wait for the smog man to smog your car. The idea is to get the cat hot and to keep it hot.

-Turn off all electrical accessories for smog, including headlights. This reduces engine load.

-Turn the HVAC temperature control all the way to HOT. This reduces combustion chamber temps and allows coolant to flow through the back of the cylinder head. If the HVAC is at full COLD the heater valve is closed, little coolant flows through the rear of the cylinder head and cylinders 3 and 4 will have higher combustion chamber temps. Leave the blower motor off.

EDIT:

So many of these cars are sent to the crusher because they fail smog, which is absolutely tragic because CA is one of the few places in the entire world where 240s are both plentiful and also can survive this long without rusting away. We throw away otherwise perfect original condition cars for no reason. 

Please keep it alive OP, it looks great and you absolutely won’t regret it.