Deep memory begins right after the KOEO, 6 seconds after, a separate "1", and 6 seconds more - then the codes stored in "deep memory" are outputed by blinks.
Balance test can be started after the KOER codes outputed by pressing and releasing brake pedal. The Codes will be: 1-8 - the number of the wheek cilinder, 9 - pass. Must be run 3 times at least, the wheek cilinder must appear at least 2 times for correct result.
Code 215: Named "ignition system fault" in service manual, but the knock sensor is connected to PCM directly. Check wiring harness at first. It will not be easy, the knock sensors are deep inside the motor.