Troubleshooting for gas mixture faults

Diagnostic codes 721 – 723, 726

Diagnostic codes 721–723 and 726 occur when there is a gas mixture failure.

Symptoms

Code Symptoms XPR® models XPR action Code cancels with...
721 There was a failure of the mixing parameter checksum. (OptiMix™ only) All models Ramp down
  • Set process
  • Remote on-off
722 There was a failure of the mixing flow calibration. (OptiMix only)
723 There was a failure of the mixing pressure calibration. (OptiMix only)
726 There is a problem with the mixing system clock. (OptiMix only)

Corrective action

  1. Use the remote on-off switch to set the cutting system to OFF.
  2. Use the remote on-off switch to set the cutting system back to ON.
  3. Make sure that all of the wire harness connections for the gas mixer module are correct and are fully tightened.
  4. If the diagnostic code continues:
    1. Replace the gas mixer module.

      Refer to VWI and OptiMix gas connect console mixer, transducers, and valves.

    2. If a new gas mixer module does not repair the problem, replace the gas connect console.