2004 Saturn, "L" series, 3 liter V-6. po300,

PO300 is Random/Multiple/Cylinder Misfire. PO301 through Po306 is Cylinder misfire detected. Sorry.

P0300 multiple misfire
P0302 misfire cylinder 2
P0306 misfire cylinder 6

PO300 and P1399 are random cylinder misfire detected.
PO301 cylinder 1 misfire
PO302 cylinder 2 misfire
PO304 cylinder 4 misfire
PO306 cylinder 6 misfire
I would say that you have damage to the ignition wiring harness or you ECM is failing.

I've had similar issues. The fix I used was to take my vehicle to AAMCO and let them run a diagnostic check. Most often it will be at little or no cost and, if you don't want to mess with the fix anymore, they can fix it onsite.

miss firein engine ,, possibly cyclinder 5 and 6.... most likely coil pack

Check and test injection system. 300 is misfirn random and 306 mifrie cyl #6

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...

P0300 Multiple Cylinder Misfire Detected

P0306 Cylinder 6 Misfire Detected

P0451 EVAP Pressure Sensor Range/Performance

I have no idea what those last two are. Typo, maybe?

Your first two codes could be caused by old spark plugs and/or leaking plug wires.

Your EVAP code could be a bad fuel tank pressure sensor or a malfunctioning EVAP system. With that code, if you remove your fuel cap and get a whoosing sound, then it is an issue with your EVAP system not properly venting the tank. If you don't get that sound, then the tank pressure sensor is bad.

These are misfire codes.This means that your vehicle is missing.The 300 is a random misfire and the 305 is for cylinder 5,and the 306 is for cylinder number 6.Check the plugs if they are good then you could have bad coils.They are top of the plugs.Hope this helps.Good luck.

Yes they could a PO300 is a generic misfire code. PO301 would be cylinder number 1 so on and so forth. check the resistance of your plug wires they should be approx. 7000 ohms per foot. it could also be a coil over plug. primary resistance of the cops should be 1-3 ohms. but since this is a misfire it would be your secondary. which should be between 20000-30000 ohms. hope I helped you out. Happy Motoring!