I’ve got a 99 Subaru Legacy (30th anniversary edition!) sedan with the 2.2L engine and a handful shy of 100k miles. She’s been struggling with some sort of electrical bug. I’ve mysteriously burned out 4 coil packs in the last 9 months, or about one every 3000 miles. 3 of the times, one or two plugs would stop firing first, leaving the car drivable but shaky.
The other time, the engine cut while I was driving and wouldn’t turn back on. Turned out I’d blown a fuse responsible for the ECM, but every replacement fuse blew until the coil itself was replaced. This leads me to envision something was running hot inside the coil pack, melted thru insulation, and shorted out the circuit leading to that fuse. Since the coil packs keep going, I suspect the electrical issue lies here.
I’ve had a P0420 code (i.e. low cat efficiency) forever, and I’ve heard this is usually caused by the O2 sensor going bad. No nasty smells, so I’m praying my cat is still good. Periodically, I get slight headlight dimming during braking. Also, right around the time the coils started burning out, my left blinker started blinking at erratic and unpredictable rates. The front and rear lights turn on at opposite times rather than in sync.
Mechanics wanted to replace my whole wire harness, but I’m not trying to blow $6,000 yet if a coil pack is only $80 and i can replace it in 5 minutes on the side of a highway. Any ideas for how to tackle this? If it helps, I’m an engineering student armed with a $30 multimeter and a soldering iron. Thanks for anything you can offer!