Code 304 won't clear new plug wirea,new coils 2002 4cyl sanoma

#4 plug,coil,wire,module.

The code 300 is a Random/Multiple Cylinder Misfire....a 302 is Cylinder # 2 misfire detected. ..and the same for 304 and 306..being 304 is cylinder 4 misfire and 306 is cylinder 6 misfire...All these at the same time normally is a faulty coil pack..,and or faulty coils...spark plugs.,plug wires.....It should be running horribly or barely ....However it could be internal losing compression.....It could just need a good tune up.....Disconnect battery before changing coils,wires..,or plugs in order to clear the fault codes.....

sounds like it is tune up time! those code are cylinder one, two and four misfire.... plugs and plug wires / boots. a leaky valve cover gasket can saturate the boots with oil and cause them to fail. so fix that too or it will wreck the new boots fast. if you have coil packs, clear the codes and swap them from cylinder to cylinder to see if the number three coil is the only good one. start with a tune up

Code 316 is an extension of your Code 304. 316 means its misfiring in the first 1000 RPM's and 304 means number 4 cylinder is the problem cylinder.
Could be a bad wire, coil, or sparkplug.

Ford- PO300 codes, do not always indicate the correct
cylinder with a misfire, or if you have several bad coils,
or one that only acts up when it wants to.

It will never be a spark plug or injector

If you look at fuel trim or smell a hot converter, you may
find a bad injector, but not for the misfire is most cases

Have you cleared the codes since replacing the parts? If so, are the codes coming back? Does the misfire still exist even after replacing the parts? You post is rather unclear on this.

If you changed the plug, wire and coil and it didn't clear the misfire, then I would look at the injector. try switching it with another and see if the misfire code moves to the cylinder that you put the suspect injector in.

I think that PO422 is the Cat Converter, it may be bad or may be just the O2 sensor.
The PO300, 302, 303, 304 code have to do with the ignition coils or wires. (302, 303, 304 means there are ignition /firing problems in cylinders 2, 3and 4). If your lucky just the wire and new spark plugs.
Google "engine codes Jetta" for more on web. Good luck.

I wouldn't worry about the 02 code it will clear when you replace the coils. to be positive that the coils are bad, swap them with another cylinder and see if that cylinder misfires. 90% of the time it's the coil. Let me know
Randy

ck if you have spark at the coil for that cylinder. check the plug wire closely. if it has spark at the coil, then replace all the spark plug wires.