Black ESP Probe, by Harman 3-20-11744;

Replaces part# 1-00-00744 Exhaust thermister probe ESP, Black Wire *You must order the same color thermister probe as the one you are replacing. The ESP constantly monitors and adjusts heat output to maintain set room temperatures within 1 degree. A 3 blink error code means that the control board has not detected the ESP (Exhaust Sensing Probe) at startup or that it lost communication with it while the unit was running. Verify that the ESP probe is clean by removing it and looking at it, clean if necessary. It should be a silver colored metal. If you replace it, make sure you replace it with the proper one for your unit. There are two versions; a probe with black wires and a probe with red wires, replace accordingly. If the probe itself looks "bent" it's probably broken. Before replacing the probe verify that the probe itself is actually plugged into the controller and the contacts on the controller are "clean" On the front side of each controller, there is a red rectangle box with a series of 8 micro-switches called DIP switches. The controller must be removed from the unit to access them. DIP switches allow multiple stoves to use the same controller but run different programs according to the stove's required functions. The #5 DIP switch must be set to "OFF' or down for ESP probes with black wires and set to "ON" for DIP switches with red wires. 3 blink error codes can be caused by installing the improper colored wired ESP with the wrong DIP selection.