my engine lite is on and i was told a FEW things could b wrong with it. on 2001 Nissan Quest

my engine lite is on and i was told a FEW things could b wrong with it..1 is knock sensor.2 power train module monitors 3 control system purge flow monitioring.. my engine just came on yesterday and is stayin on its not flashin just stayin on constant

Asked by for the 2001 Nissan Quest
1 answer
i would not worry about the knock sensor code right now. it seems to always come on when another code sets with no problem.
the evap purge flow requires a smoke testor, scan tool and volt meter to determine the issue. if you have the tools, good, if not then you need a shop to check this out.
what was the code number for the monitors?? I know 325 is the knock sensor and the evap is a 400s code but what was the third code number??

Roy