code problems

[RookieMT]

Hi my brother in law brought over a 92 trans sport the other day,I have ran the code test and this is what I found,I dont know what they mean or if they are important,could you let me know?
code: 16
17
18
21
42
43
56
I did find what they are but not what they do!I had the battery charger on it when I tested so that is probally why the 16 came up,but I dont know the rest,please help!
Aaron

[LMP]

As I understand, you have the meaning of the codes. anyway, they are available here and from the numbers, I assume it is a 3800.
www.avigex.ca/xport/3800codes.jpg
and where they come from:
www.avigex.ca/xport/dtc17.jpg
www.avigex.ca/xport/dtc18.jpg
www.avigex.ca/xport/dtc21.jpg
www.avigex.ca/xport/dtc43.jpg
www.avigex.ca/xport/dtc42.jpg
www.avigex.ca/xport/dtc56.jpg

in fact, just go to
www.avigex.ca/xport
and you can browse through all of what I posted there.

In as much as "problems" with that car, first question: how does it behave? If all seems OK, then ALl these codes may have been generated at some "critical" moment and be meaningless now but it may mean that when something starts being strange with the car, suspect these components.
You should also clear the codes because you do not know for how long they have been there. If there is a real problem they will come back anyway.
Disconnect the battery, and turn on ignition and headlights..of course they will not light up, but this is to be sure to evacuate any residual charge that might keep the memory alive. Wait a few minutes, say 10.
After that, the codes should have vanished.
Check for codes after a few engine cycles.
As you said, 16 is lo/hi voltage, and you'll have time to know if the battery dies; a simple check with a vltmeter to check operating voltage will clear any doubts here (around 14 V with engine running and warmed up: in very cold temperature, the regulator will provide higher voltage at startup - in the 15's, but it will taper off around 14 after a few minutes).
COde 43: check if knock sensor is connected.
COde 56 is linked to the EGR valve, a common problem. Again, if car goes OK and you have no idle problem, just live with it cause the EGR valve costs 150-200 and if you have the code and no problem, it means one section does not operate but it has failed closed. (failed open, you would have erratic idle).....
OK for now, come back with any other question