SLC Free 2 Accuracy

Hi, I have a couple of SLC Free 2 boards that read differently to my benchmark controllers.

The benchmark controllers from another vendor read AFR 14.7:1 as expected when mounted in my exhaust tail pipe with a probe, however the SLCs are both reading around 17:1, which coincidentally is what they read without a sensor plugged into them.

I am using genuine Bosch sensors.

Is there something I need to do to calibrate the controller?

Edit - For the record, I am testing with 2 benchmark controllers from another vendor and 3 sensors, the output from all of these is the same.

when the sensor is in free air does the AFR so max lean of 20 AFR?

Free to air reading is 28:1

can you take a picture of the LCD with the sensor in free air and post it?

Can you please do the test below and post the result

Sensor Test with Lighter Gas

  1. Remove Sensor from exhaust
  2. Connect the sensor to the wideband controller and power on the wideband controller
  3. Wait about 2 minutes, the sensor should get hot (be careful)
  4. With a cigarette lighter, give the tip of the sensor some gas, do not light the gas. With enough gas, the wideband controller should output max rich (~0.68Lambda, 0v on linear output), please confirm this