So after a cold night at work, I'm driving my car and after I leave the parking lot and am onto the highway, I notice my acceleration is a little weak and my check engine light is flashing. So, in order to get off the highway, I gave the car some gas and it vibrated a bit before picking up speed. I pulled into a parking lot and poked around under the hood, and pushed the wires going to the cylinders a little tighter (they were slightly loose) and checked the oil level. It seemed a little low. So I shut off the car and waited 5 mins, and when I turned it back on, the check engine light was lit steady. So I carefully drove somewhere to get some oil, and it drove fine for the most part. I took it for an oil change and they said I badly needed an air filter, so I got that, and now the cars driving okay (so it seems) but I don't know if I should worry or avoid the expressway. They said they didn't know what the check engine code was (I had the oil done while getting new tires so it was at a tire shop). Any ideas?

 

Is the check engine light still on? If so, go back to the automotive store (if your car is in good enough condition to), and ask them to do a free obd scan for you. Then go from there. Also, what is the model of the car.

 

What year Civic? A blinking CEL indicates engine misfire severe enough to damage the catalytic converter. You definitely don't want to drive under this condition. If the Civic is 92-00, then you can pull the CEL from the ECU at home by the jumper wire method described at the link in my signature. This can be done even if the CEL is no longer lit.

 

Sorry I left out some obviously necessary info, its a 1998 Civic LX 4dr. The light has been on and steady since I restarted the car that night. At the tire shop, they said all they noticed was a bad air filter, which they replaced. I've driven about 35 miles since it happened, 10 of them after the oil and filter change. I haven't pushed it or anything but city driving below 50mph has been perfectly normal.