I bought a Subaru two years ago and it’s a great car for me but the original owner is from Texas and I live in Montana where it gets really cold in the winter and my car struggles to start when I don’t park it in the garage. Last year I could just use my parents’ garage but I moved out and I don’t have a garage. I replaced the battery earlier this summer so I’m pretty sure it isn’t a battery problem but I was wondering if I need to take it into a mechanic or if there’s another part I should consider replacing?
If the engine cranks at normal speed, then failure to start is most often caused by worn out spark plugs, a bad engine coolant temperature sensor, carboned up throttle body or low fuel pressure.
A cold engine needs more fuel to fire up. If the coolant temp sensor is giving bad readings, the air/fuel mixture will be too lean. Low fuel pressure can also cause hard start in cold weather. Compare engine coolant temp sensor readings to actual engine temp. Do a fuel pressure test. Make sure the spark plugs are good