21 error codes at once

[titanium melter]

2003 Avalanche 1500 reads 21 codes at once. Abs, wheels speed sensor, 4 wheel low interlock, o2 sensor, generator over voltage, ECM failure codes, drive shaft sensor, and many more. What could possibly cause this many codes at once. Alternator replaced 7 days ago.

[efritz]

Clear them all, see which ones come back, and go from there. Been there many many times.

[gmtech4]

Clear them all, see which ones come back, and go from there. Been there many many times.

what he said ^^^^^^^^^^^

 

take it in regardless ,your done trying to fix this unless ya have a scanner and service information

[Doug_Scott]

Why was the alternator replaced? When you get a number of codes almost at once, and they are not all in the same system, you are pretty much assured it is a false positive.