E4 two or three times a day


As the title says. Controller is probably 10 months old. E4 message ( probe temp difference more than 0.5 °) with all the alarms every day, two or three times for ahout 4 months. I’ve moved the probes. And again. And again. It seems to work otherwise. Any suggestions?

Thank you

May I know that are you using the ITC-306A?
E4 means the temperature difference between 2 probes is bigger than 3℃/5℉.
It is best to place the two probes together.
Could you please clean the probes and cables, then use a hairdryer to dry the entire unit for a while, then test the probes in the air temperature, will it trigger the E4 alarm?

Yes itc 306a. Cleaned and dried the probes. It didnt trigger the error, but it is the only heater in the tank so i only left it out for about an hour. There is no reason to buy a controller with two probes to put them in the same place… one probe is in my sump, and the other is in the tank right in front of the return… it triggered the error twice at 7 am this morning and then again at about 3 pm. I cant leave it out of the water for 8 hours at a time as it is 40°F outside and the temp of the tank will plummet.

Thank you

After turning it off yesterday, it has gone “offline” 4 times that i am aware of, and then within a little bit it gets back online. I’m thinking its possesses. Time to buy a different brand?


Maybe you could try putting both probes in the same position? This can rule out whether the problem is caused by the temperature difference of the water tank.
According to the suggestion of other customers, Inkbird pro app has added offline notification function. If the device is offline for more than 45 minutes, it will remind you. If you don’t need this function, please turn off the offline notification function through the settings of inkbird pro.

It does it out of the water with the two probes side by side. I bought a new controller so i could remove this one for testing. Its also saying abnormal heating time, and randomly going offline and coming back. A ghost must be inside.

E5 is continuous heating time alarm. Perhaps this is because the temperature has not been able to reach the heating target value when testing at room temperature.
As there is no specific data, let me give an example: T1=76, T2=81, CT=3

  1. The temperature reached/ lower than 76 degrees, the ITC-306A turns on the outlet, but the heater did not heat to 81 degrees within 3 hours, it will alarm and shows E5.
  2. The temperature reached/ lower than 76 degrees, the ITC-306A turns on the outlet, the temperature is heated to 81 degrees within 1 hour, then the timer (CT) stop. When the temperature drops to 76 degrees, it will turn on the heater again and restart the CT (3 hours).

Please set T2 to be the same as or lower than the room temperature. The value of T1 is set lower than T2.
Then please test whether the probes will trigger the E4 alarm.
If yes, there may be a problem with the probes of ITC-306A, please contact the seller for after-sales processing.