Originally Posted by
Jaxom
I looked this up on AllData because the concept of a 4-wire wideband didn't sound right to me. On an '05 Ram 5.7, having 4 O2's is an indicator of Cali emissions, Federal emissions trucks only had 2 O2's. However, according to my information, they both use narrowband sensors. Also, I have never seen an O2 heater that operates at 7 volts. They are always 12v circuits, and normally on their own fused circuit.
Are you sure your meter is accurate and that you had a good ground when you checked this?