'02 normally aspirated 2.9 -

P0050 HO2S Heater Control Circuit (Bank 2, Sensor 1)
P0300 Random/Multiple Cylinder Misfire Detected
P0305 Cylinder 5 misfire detected
P0304 Cylinder 4 misfire detected
P0306 Cylinder 6 misfire detected

Can the O2 sensor cause the 300 series codes?

Does this vehicle use 1 or 2 forward O2 sensors (left and right)? If 2, which does the 0050 indicate?

Thanks.

R Stuart

I hope someone else chimes in, I don't do well with the 6 cyl engines.

The O2 sensor is for the right side of the car, yes there are 2. It needs to be replaced. It is possible that the O2 sensor caused all of this, OR that the crud that is passed through the exhaust unburned coated the O2 sensor.

The P0300 will cause the blinking CEL.

Since all 3 misfires are on the right side of the engine, I would look for other causes. Like a bad CPS, injector relay, exhaust leak before the CAT, etc. I would rule out coils, just because a triple failure is unprecedented.
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My name is Klaus and I am a V♂lv♂holic

Hi Klaus,

Interestingly, it misses (sounds like Gene Krupa on glass packs) when idling, but under load is pretty smooth. I can drive it 40 miles on the highway with no issue, but when get off and stop it starts percolating again.

When I first got the miss codes for cylinders 4 and 5 I replaced those coils - to no avail.

Do you think this could be from a sticking valve? How would that work?

Thanks.

R Stuart

Valves really don't 'stick', they get so dirty that it won't close properly. The engine is designed to spin the valves at above 2000rpm, helping to keep it clean. Also, regular gasoline does not contain cleaning agents like the 89 and 91 octane fuels do. You might want to pour 2 Techron bottles of injector cleaner into a full tank. Or try some Seafoam cleaner treatment in the intake manifold to clean off the combustion chambers.

Before you get all caught up with ideas, get a compression reading on a warm engine. That will tell you a lot.
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My name is Klaus and I am a V♂lv♂holic