Misfire OBD II code [Q]
 

My friend w/ an 02' LLBean OB wagon (H-6) just got an MIL code I pulled, two actually:

P0301 Cylinder 1 Misfire Detected

P0303 Cylinder 3 Misfire Detected

Anyone have experience with these codes? The dealer says possibly the sparkplug(s)in which case he'd have to pay because it's a wear item they say, or wires / Coil(s) they pay. He's at 32K or so. Just wondering what others have seen here.

Also, has anyone done a sparkplug change on an H-6? Is it tough? I haven't done the ones in our H-6 yet and I'm curious.


TIA

Peaty

I started getting that same code, well the #1 misfire not the #3, on my 2.5GT about six or eight months ago. It was about the same time as the mystery overheating problem started. Are the H6 engines prone to the same weak head gasket problem of the 2.5? I haven't gotten the code again since replacing the head gaskets. Granted, it has only been a month or so. It could crop up again.

I don't know if there is a head gasket problem with the H-6 or not. I don't remember seeing that it is but the number of H-6's compared to the H-4 is small. I hope that not the problem. How did they determine it was a head gasket? Did they use an HC sniffer in the coolant?

Actually, I asked the folks here why my engine was overheating. Three of them came back with something like "oh no, the dreaded 2.5 head gasket!" Then I had the coolant sniffed and it was confirmed.
I don't know if the blown gasket caused the "misfire" code, but I haven't gotten the code again since the new gaskets. Might have been a coincidence and I'll get the code again soon.
Anyone else want to chime in? I've got my Nomex boxers on if you want to flame my "diagnosis."

My friend just called me and said there is a TSB (I don't have the number yet) that involves sending the ECU back to Subaru to be re-flashed. I'll report back when I get more info.

update
 

He got his car back with the re-flashed ECU and the CEL hasen't come back so far. He said he also had a slight hesitation when he stepped on the gas before the re-flash (he had them look at that previously but they couldn't find anything wrong) it seems to be better now, could have just been the ECU reset though, we'll see.