P0138 GMC -

Question

I is showing the code PO138 low voltage. Is this a bad unit or connection? the OE has 188,890 miles on it. Should I check the connection or replace it.

Answer 1

Hi there,

In most cases the problem is with the sensor. The circuit fails internally and this causes the codes to appear.Always inspect the connector when you are doing this type of work, but generally speaking it's usually the sensor itself that fails.