ThunderMax Oxygen (O2) Sensor Operation Testing - Manual (Page 6)

If you are getting a constant AFR reading of 9.30 on both cylinders, the ECM is not
getting a signal from the Data Port on the O2 Module.
How to Check:

Check plug for connectivity- Make sure to use dielectric grease and that it is
‘Snapped’ together securely.

Make sure it is plugged into the correct plug on the harness-Wires should
be Black, Gray, Green w/ Violet Stripe

Test to make sure plug has 12 volts- Using a Voltage Tester, attach
Positive
clip to GRAY, and Negative clip to BLACK(ground).
Note: You must use the ‘Ground’ inside the plug to properly test plug.