Hey guys,

Just to preface, pretty dumb when it comes to cars. I can top up oil and change a tire, that's about it. I tried searching for this, but I don't really know the right terms.

My 2012 Civic EX has been running "heavy" for a couple of weeks now. And especially when I'm first driving it for the day, it has like this stuttering sound. Like a shitty motorcycle? It consumes more fuel when I accelerate and slow down, it seems to put off an odd sound when I'm idling (which I can only hear when I pop the hood open). If it would help, I can upload a video of the sound.

A couple of days ago, I tried googling how to check the coolant levels, and I popped the black cap on the side of the hood closer to me. I guess I never sealed it properly because smoke/steam started coming from it after 40KM of driving, so i went back and took it off and made sure it was secure. Steam was still coming when I drove home, again near the tail end of my trip. It's been tapering off to less and less over the past few days, and today it was minimal. Nothing unusual from my exhaust.

During my drive home today, the high temperature light came on for a few seconds. I was going about 80km/h, slowed down for a bit, it turned off and I drove like normal and it didn't come back on.

I want to settle this so I don't have to pay for some expensive repairs, which I can't afford at the moment. I do want to take it in for service, which I can't until I get paid in 4 days. What could it be? Some info:

Last Honda servicing was probably a year ago
I've been topping up oil myself 0W-20
Coolant level is between min/max
112,000 KM