View Full Version : ses light: p0300 multiple cylinder missfire

08-06-2012, 10:14 PM
please help me with this code, my car has ran fine for over a year now and as soon as a did an underside wash at the car wash i started it up and ran so bad, so i went home and scanned it and it threw p0300 multiple cylinder missfire. I know it has to do with washing the underside of my car because it ran perfect before with no codes and as soon as i washed it the ses light is flashing, please help!

08-06-2012, 10:24 PM
pretty simple, you shorted a coil or got water in one of the ignition connectors. let it dry out, it should be fine.

08-06-2012, 10:37 PM
coil? and what ignition connectors this sounds like it is what my problem is because I went to turn it over everything in the cluster lit up like normal but when i turned it over everything went blank, but if i wait long enough it will start, so what and where is the ignition connectors? thanks.

08-07-2012, 07:26 AM

08-07-2012, 07:37 AM
is it still doing it? If so, try leaving the car outside with the hood up and all the fuse covers off for a few hours.

08-07-2012, 09:28 AM
I would go thru the engine bay and unplug all large major connectors and look for water inside them. Definately check the crank position sensor plug if it wasnt working well could cause odd misfires. If you lost all power check the battery connections as well make sure they have a good connection.

08-07-2012, 02:31 PM
Yep still doing it and where is the crank sensor?

08-07-2012, 04:56 PM
Could it be vats? I have a security light when it wont start sometimes?

08-07-2012, 07:56 PM
VATS has nothing do with that Check Engine Light.

Check spark plugs, coil packs and spark plug wires first. If they all check out, post back and we'll give you more advanced stuff to check.

08-07-2012, 09:17 PM
o2 sensors- get a reading on them.

08-07-2012, 11:01 PM
I reset the code and dried everything out real good and drove it for five minutes and all was fine, we'll see if the problem happens again, this is the second time it has done this in two years. Weird.

08-08-2012, 01:37 PM
Are your spark plug wires new, old, still the stock ones that came on the car? You might have some cracks in them that are causing your problem.

A little water isn't going to affect your spark plugs. If it runs fine now that it's dry you probably didn't blow a coil. Blowing out a coil due to water would be a secondary result of a bad spark plug wire.

I would be thinking about changing the plug wires myself.

08-08-2012, 11:55 PM
Im running stock wires with e3 plugs

08-09-2012, 01:19 PM
Im running stock wires with e3 plugs

If they are the same stock wires that came on the car they are 10 years old, change them, it's probably your problem.

08-09-2012, 02:43 PM
My wires were fine when this happened. For me, the coil pack didn't click in all the way to the wiring harness and I was too tired to hear a problem after having been up for 27 hours (drove it home about 60 miles on 4 cylinders...yeah that was bad)

If the issue continues my steps would be
1. Check that coil pack is connected to wiring harness
2. Check wires are in good condition and tight
3. Check plugs are tight
4. At that point you may need to start replacing stuff, i.e. coils, plugs, wires.

Might as well look into as much as you can without spending money until you have to, but don't continue to drive it a lot if it's throwing those codes.

08-13-2012, 09:39 PM
how can i get a reading on my 02 sensors?

o2 sensors- get a reading on them.

08-13-2012, 10:40 PM
o2 sensors will not set a p300 code without setting a o2 sensor code.

did you ever replace your ignition wires? if so with what brand cause if its anything other than gm,msd or another higher priced brand your looking at about 1 year life span. plus the e3 plugs are prob the worst plugs you can buy on the shelf no offense. i worked at a advance auto for years through college (no im not the stupid fuck they put behind the counter that doesnt know shit about cars). ive seen it ALL. get some msd wires and some ngk plugs and your miss fire will go away. unless you have 2 or more coil packs on their way out. but my money is on the wires even if you did do them not to long ago.

08-13-2012, 10:42 PM
and your ignition switch or your security chip in your key is going bad and that will cause the vats to cut the fuel to the car and make it not start

08-13-2012, 11:05 PM
I just ordered msd and ngk. I think my vats must be going out to because once in awhile it will act like a dead battery then after i wait a few minutes it will start fine

08-14-2012, 08:55 PM
well if your actual vats is kicking it will turn over but it cuts the fuel to the motor but if your switch is going then itll do exactly what your explaining.

08-16-2012, 06:53 PM
thanks, where is the switch?