B error codes VRF - temperature sensor malfunction - MCMX, MCSX, MCHX, MCRX


  1. Check Connections: Ensure all sensor connections are secure and free from corrosion or damage. Loose or corroded connections can cause erratic readings.


  2. Inspect Wiring: Look for any signs of wear, fraying, or damage in the wiring. Damaged wires can lead to incorrect sensor readings or complete failure.


  3. Test the Sensor: Use a multimeter to check the sensor’s resistance. Compare the readings with the manufacturer’s specifications to identify any discrepancies - see below






RT1 to RT6 are all 20k ohm resistance.

Check sensor resistance: 

  • If the units have been off for a while, the resistance between these sensors should be similar.
  • Identify the sensor with a noticeably different resistance.
  • Check the integrity of the cables connected to this sensor

Trace Sensor Wires:

  • Each sensor typically has different colored wires.
  • Use these colors to trace where each sensor is connected.


Sensor replacement:

  • Note that sensor replacements for RT1 to RT6 come in kits of three, not individually.


RT7 is a 15k ohm resistance

RT8 is a 50k ohm resistance