Hi. First I did do a search but nothing addressed my particular issue.

I just picked up an 04 MCS with 75K on the clock. Yesterday the DSC and SES lights came on. Car ran fine, no limp mode. Next time I started it the DSC light went out but the SES stayed on. Read the codes and came up with:

P0304-Cyl #4 Misfire Detected
P0500-Vehicle Speed Sensor
P1692-Electronic Throttle Control Monitor Level 2/3 Motorized Throttle Control and Fuel Injection Switch Off 'A'
P0313-Misfire detected with low fuel

I cleared the codes and the SES went out. Drove about 50 miles with no problems. Then the DSC came on. When I stopped and restarted the car again the DSC went out. Next time I started the car the DSC and SES came back on but the car ran fine. Read the codes again and got a P0304 code. Car is running fine. Ideas? I've seen some things on here about head gaskets and a P0304 code so I'm nervous!!

Thanks!!

 

Not likely, first check all the connections to plug #4, (at the plug, at the coil, and the wire itself) look for loose connection or corrosion.

It only sounds like a slight missfire, I would pull the plug, check it & swap it's position to see if the missfire moves (also try switching the plug wire with the other one thats close in size, just remember not to do them both at the same time to help you isolate the problem, and to put things back if nothing changes)

The reason I think it is slight is because it seems to be enough to be noticed by the ECU (dsc) but not enough to give you an SES while driving, just a little notification later. (when you restart, mine does it like that all the time.)

 

Well that's good to hear. Funny that the DSC light can be triggered by a misfire. I would think that would be reserved for a speed sensor issue only. I'll try your suggestions. Thanks!!!

 

OK, changed the plugs. #4 was defiantly bad, but they all were worn. Hope that fixes it. at least it seems like it has a little more power!