Exhaust Sensor detects Vent Temperature is Greater than 190oF (88oC).
This Error Code will go away when the condition is remedied.
If Error happens again:
1. Check if dip switch Max Fire setting is ON. Switches 6 and 7 should be OFF for normal operation.
2. Check exhaust temperature sensor. Ensure connections are secure.
3. Check sensor resistance. If resistance is zero, replace the sensor.
4. Check exhaust vent for blockage.
5. If the problem persists, replace the control.
6. If the problem persists, replace the heat exchanger.
