Hello. If there was no engine light prior to you completing the spark plug job, then you should be fine. When you start any vehicle without something plugged in, your definitely without a doubt going to receive a check engine light as the PCM is detecting some type of malfunction. In this day in age it’s always good to have a code reader/OBD Scan Tool. This will insure you know exactly what’s going on with your vehicle without second guessing. In your case a scan tool would tell you that there was a cylinder misfire and you can either erase the code or simply wait sometimes and it will eventually turn off.. But not all the time. You can also use the battery/PCM disconnect method, but please be aware that resetting your PCM will require roughly 200 miles driven for the computer to gather its information for the vehicle to be ready for an inspection. If you have no upcoming inspections you will be fine resetting the engine light. Hope this helps.I decided to change my spark plugs last night as it is nearing almost 100k miles (95k) and for preventative maintenence. I did everything right but when I started the car, I started it with one of the wires unplugged to the coilpack accidently causing a check engine light. This resulted in a check engine light and misfiring. I turned it off and plug it the wire back in and started it again and stopped misfiring but the check engine light is still on. Does this mean that there is still a problem or do I give it a day or two to let it go away on its own? Help please!