2004 1,6 #4 CLY MISFIRE CHANGE COIL PACK PLUG AND WIRES PO300 AND PO304

If a tune up (spark plugs, ignition wires, distributor cap/rotor button or coil packs) don't work, try checking the fuel system.

THROTTLE POSITION SENSOR, MISFIRE, #4 MISFIRE, KNOCK SENSOR, THESE ARE YOUR TROUBLE CODES, PO120,PO300, PO304, PO325, RESPECTIVELY, REPLACE THE TPS @ THROTTLE BODY, REPLACE KNOCK SENSOR , @ ENGINE BLOCK, REPLACE YOUR SPARK PLUGS & PLUG WIRES ! AND YOU MUST ALSO REPLACE BOTH YOUR AIR & FUEL FILTERS, DISTRIBUTOR CAP & ROTOR , INSPECT, MAY NEED TO REPLACE, I WOULD ANYWAY !!!!!!!! ADD SOME GOOD FUEL INJECTOR CLEANER TO TANK, NEXT FUEL UP !

Would need my head under the bonnet to find the answer ,from your description it could now be a injector who knows but take the plug out and see if its all wet and black then go from this point as fault could be a coil pack /valves or fuel injector but as you havent stated year then again it could have a coil on each cylinder or a remove coil pack as you stated it has HT leads (wires)

there is a lot issue with this motor with the po300,po303 ,po304 . it has the do with the head and valves. you need to found out which cylinder is mis firing

The code you got may not have indicated the correct coil, that was bad

I would put the old coil back in #6 & either walk the new coil to another cylinder, or get professonal help in the form of a scan tool in Mode $06,
if applicable on your vehicle & check for misfires that why

Forget the PO300

PO 300 is multiple misfires detected
PO 301, 304, 305, 306 are misfires in cylinders 1,4,5,&6
PO 053 is HO2S Bank 1 Sensor 1 Heater Resistance
PO 106 is MAP/BARO CKT Range / Perf
PO 316 is Misfire detected 1st 1000 Revs.

On a misfire, I usually push towards the spark plugs, plug wires, and coil packs / distributor coil.
You have PO 106 and PO 053 that need to be inquired about at nearest AutoZone.
They can give you an idea as to what is the problem on these.

Did a MAP sensor **** out and cause all the misfires ?
Did a misfire cause the MAP sensor error?
You see what I'm saying ?...Something caused all the misfires...thinking MAP...but not that familiar with the function of the MAP.

Hope this helps...

If you get
P0300
P0301
P0302
P0303
P0304
P0305
P0306
P0307
P0308

error codes and
you have an engine that misfires or runs rough, it can be the injector for that
cylinder or the coil pack. The P0300 code is a random misfire code and may or
may not be the above. All the other messages are for misfire of a particular
cylinder indicated by the last digit.

Test the coil pack by switching it to another spark plug and
see if the problem follows to that cylinder.

If that makes no difference, it is very likely the injector.
Disconnect the injector connector of the same cylinder and measure the
resistance. It should be 13.5 to 14.2 ohms at 70 degrees temp. It can be up to
16 ohms if the engine is hot. If you see a really high resistance or an open or
short then you can try to change the injector. If not, you can remove the fuel
rail on that side and switch the injector to another cylinder and see if the
problem follows to that cylinder.

You
need a 22mm wrench to remove the fuel pressure regulator. The other connections
are std. When all screws are removed, GENTLY wiggle the rail up and guide it
smoothly out. Don't put any sideward stress on the injector bodies.

Here is how to identify cylinders

Front of vehicle ^

1........2
3........4
5........6
7........8

All of the
injector connectors have a Black with red stripe wire. The corresponding other
wire color on the injector connector that matches with above are

red.........................white
green......................Red/black stripe
blue........................yellow
blue/red
stripe..........Red/white stripe

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.

po300 is random misfire detected from the ecm. could faulty spark plug wires or coil causeing the problem. also check spark plugs as well. use a inline tester to check fire from the coil to plugs. if fire from coil is good on each plug then change the plugs. hope this will help you!!!!

might be the coil pack is bad, wires, plugs, o2 sensors, dirty injectors, catalic converter ( only if you smell rotten eggs ) . cylinders are misfireing.