Recently I bought an OBDII Bluetooth adapter to monitor my Tahoe's engine performance and see extra/more exact info from the ECU. Currently my o2 sensors are giving conflicting readings.

What do I mean? Well the pre cat sensors at idle were reading a F/T of -1.6% for both the 1x1 and 2x1 sensors. While the post cat sensors are reading a F/T of 99.1% for both 1x2 and 2x2 sensors. Based on the info I've learned these readings are impossible. Does any one have an idea whats up with these readings? I have been getting a p0340 cat three way inefficiency code for the pass side cat recently, but the code keeps going away even tho its a major code that should stay in the ECU for a long time.

Pic from torque app at idle:
Click image for larger version. 

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