6 720 608 257Troubleshooting21Display Cause SolutionE9 Temperature limiter opened circuit (overheat).Trips at 220F (104C).Check connections. *Check heat exchanger condition.*EA No ionization during safety time (safety time out).Note: appliance makes 3 ignition attemptsbefore entering error mode “EA”.Check gas pressure. (see chapter 2.9 ) *Check that gas is not diluted with air, as aresult from recent gas pipeline rework.*.Check if vent terminal is blocked (especiallywhen the appliance starts up for some sec-onds and then looses ionization signal).*Check ionization electrode.*Check for a proper ground.*Check CO 2 levels.* (see chapter 9)EC The ionization signal momentarily disappearedmore then 5 times in less then 30 seconds. CO2may be out of adjustmentFA Leakage error (gas valves do not close gascircuit).Check gas valve and control unit.*F7 Ionization error (flame sensing at stand-by). Check control unit.*E0 Internal software/hardware failure. Check control unit.*A7 Hot water temperature sensor/receiver defect(from control unit).Check water temperature sensor/receiver andconnections.*Check incoming water temperature to heater, itmust be above 32°F (0°C)A9(flashing)Hot water temperature sensor/receiver mis-assembled (from control unit).Note: if display shows “A9” flashing, theappliance can be operated normally, butperformance may be affected.Check that the water temperature sensor/receiver isproperly assembled on the horizontal of the hotwater pipe.*Check that the water temperature sensor/receiver isfree from corrosion or moisture.*C1 FAN rotation too low at start-up (from controlunit).Check supply voltage.*Check fan and connections.*Check control unit.*Check if vent terminal is blocked.*C6 FAN rotation too low at operation (from controlunit).Check supply voltage.*Check fan and connections.*Check control unit.*C7 No rotational speed sensor signal from FAN Check fan and connections.*Check control unit.*CA Water flow signal over specified maximum value Check water valve and flow sensor.*E2 Inlet temperature sensor fault Check water temperature sensor/receiver andconnections.*Check incoming water temperature to heater, itmust be above 32°F (0°C)A2 Overheat protection fault Check connections to the overheat protection.*Check sensor continuity.*Check heat exchanger sealings and walls.*Table 5* By installer or service technician only.