Error Code 11

EC11 or Error Code 11

An 11 error code is an ignition failure. In other words, the unit recognizes there is a demand for hot water but for some reason is not able to ignite. This usually means there is no spark or insufficient gas entering the burner for ignition. In some cases the 11 error code could also occur when the unit ignites but fails to detect ignition via the flame rod.

The first step in troubleshooting is using the small sight glass built into the burner to observe if the burner is actually failing to ignite or failing to detect ignition.

If the unit is failing to ignite then you are missing one or more of the 3 things needed for combustion:

Air
Gas
Spark

With tankless units, you can almost always cross off “Air” as one of the contributing problems because simply removing the front cover provides the unit all the combustion air it could need. It’s still a good idea to visually inspect the cleanliness of the unit though as excessive dust, dirt or lint build up could indicate a contributing factor.

Now you are left with just Gas and Spark. One or possibly both of those are missing and that’s why the unit is not igniting. More often that not, the ignition rod has accumulated build up preventing a spark from happening. The ignition rod can be pulled out and cleaned off with the rough side of a sponge or a dollar bill. In some cases the ignition rod might have severe corrosion or pitting that renders a cleaning ineffective and it will need to be replaced. Additional causes of no spark are failed high voltage cords, a failed igniter and least likely but still possible a failed circuit board not sending voltage to the igniter. Troubleshooting is a process of elimination, start from where the spark occurs and work you way back to the circuit board. Chances are you will find the problem well before the circuit board though.

If you have spark then you’re looking at lack of gas as the cause. This could be related to a component inside the heater but also factors outside of the unit can prevent the proper amount of gas reaching the heater. Those could be the gas meter, gas regulator (if applicable), gas line, gas shut off valves and in earthquake prone areas such as California, an earthquake safety shut off valve.

Troubleshooting gas issues should be left to a professional as there is some serious risk if you’re unfamiliar with what you’re doing.

If the unit is igniting (you can see flame through the sight glass for a moment) but still giving an 11 code, that means the unit is not detecting flame. The flame rod which is usually part of the ignition rod assembly or close to it might have build up that is preventing detection of the flame. It can also be cleaned the same way as the ignition rod. Additionally make sure the blue wire attached to the flame rod is connected and not damaged, pinched or broken. Finally the flame detection system relies on proper grounding of the unit so all green ground wires should be securely attached to the various grounding points inside the heater.