Knocking sound and***** motion

This engine is picky about its oil so there could be internal damage from running it low. Also, when the Check Engine light turns on, there will be at least one diagnostic fault code stored in the Engine Computer. That code will lead you to the circuit or system with the problem, not necessarily the defective part. Many auto parts stores will read those codes for you for free.

What I think they want you to do is measure the resistance to see if it's partially shorted but this is going to be very inaccurate. Put the meter on the the lowest Ohm's scale. If they use symbols, it's the symbol shown below. Use the X1 scale. That means whatever you read is the actual value. When you put the two meter leads together the reading should be real close to "0". You're actually measuring the resistance of those leads which could be two or three ohms. Next, put the probes on the two little terminals in the connector then see what it's reading. The specification is 0.4 to 0.6 ohms which is too low to measure accurately. A better test, if you had a certain cylinder misfire code, is to switch that coil with a different one, then see if the fault code indicates a different cylinder. If it does, replace that coil. If the same cylinder has the misfire, it has to be the injector, spark plug, or one of the valves. There could also be worn piston rings. That will cause the Engine Computer to detect a misfire due to the lack of power from that cylinder but you won't feel it in the car. A compression test will identify the weak cylinder.