1990 Nissan 300zx- codes 32, 33, 34, 51 and 13.
32 and 33 are EGR related
34 is the knock sensor
51 is fuel injectors (turned out to be the harness/connector)
13 is coolant temperature sensor to the ECU
The last two I fixed, 32, 33, and 34 come on and off at random, doesn't really bother me...