Heys Guys, Im new to this board but have owned 5 Subarus, and this misfire condition popped up in the wife's Forester last summer and after 5 months, I finally resolved the misfire condition.
It started with a 301,302,303,304. I tested the coil and it tested bad on secondary resistance. Logically, I bought a new coil at the dealer assuming this would solve the misfire since I keep this car well tuned up. I replaced the upstream o2 sensor,check the plugs, plug wires, injectors etc.
No, this misfire continues at random intervals.
After we move here to SLC, I finally get tired of hearing the wife complain, I take it to the dealer(big mistake) the little kid tells me its the coil pack. I tell him that coil pack on the car is less than a month old so it cant be.
I let him install the new coil pack, and two days later I'm back at the dealer with the check engine light(301,302). The dealer says that they will look at it again, nope I swap the coil pack in front of the service manager and tell him to give me my money back since they didnt solve a thing.
They give me my money back and the car runs fine for three months.
Okay, so one morning in the cold of winter, the check engine light comes on, and so for the millionth time I hook up the code reader and get the same 300 series codes, but this time while the car is running, I check the plastic connector that plugs into the coil pack, and while its snapped in correctly, the contacts are loose.
I drive it to a small import shop and $25 later the problem is fixed. They tightned the connectors and 5k miles later and no check engine light. I don't know if this helps but it was a very frustrating issue that I am very glad is finally resolved
Be McMIllon
