Harman Black Thermister Exhaust Sensing Probe (ESP), 3-20-11744

SKU 3-20-11744
MPN 3-20-11744


Harman Black ESP Probe
  • 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.

Replacement For Part Number :
  • 3-20-11744

UPC #: 652174647279

Compatible Models


  • Accentra Cast Free Standing
  • Accentra Insert
  • Advance
  • DVC 500
  • Invincible Insert
  • Invincible RS
  • Invincible T
  • P38
  • P38+
  • P61
  • P61A
  • P68
  • PB105
  • PC45
  • PF100
  • XXV



Assembly Instructions For Harman Black Thermister Exhaust Sensing Probe (ESP), 3-20-11744

You must be careful not to bend an ESP probe if removing it for maintenance purposes. Bending the sheath of the probe will usually ruin the sensor. Likewise, when cleaning your stove, care should be taken to not bend the sensor when cleaning. Do not send brushes or vacuum tools through the stove blindly. Before cleaning your stove for the first time, find the ESP probe and make sure that it is not going to be in the way when cleaning. If it is, remove it from its mount prior to performing work.

Using a 1/4" socket, remove the mounting screw and remove the thermocouple from the stove. Trace the wires back to the control board and unplug the wires.

DIP Setting by Stove Model

Helpful Tips

The Control Board/ESP combination is responsible for all high limit safety control. There are 2 high limits, one normal operation high limit and one backup high limit. The control has an automatic diagnostic circuit that continuously monitors the ESP and Room Sensor for faults. If a fault should occur, the control sends a status alert and at the same time the unit goes down to minimum feed/ minimum burn as a safety condition.

Red thermocouples can be use in place of black thermocouples if the #5 DIP switch settings on the control board are set to 'ON', black thermocouples have the #5 DIP switch setting 'OFF', however; red thermocouples are slightly larger in diameter than black ones and often will not fit into the mounting holes of black thermocouples.

Thermocouple wires cannot be cut and spliced.


Unfortunately, sometimes products do not work like they are supposed to. We offer a 90 day warranty on manufacturer defects. Some manufacturers make this a very simple and easy process unfortunately others do not. Items must be used in accordance with the manufacturers guidelines to qualify for warranty replacement. Please be advised that warranty claims for these parts may take up to 4 weeks for processing, and customers must cover shipping.

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Customer Reviews

Based on 2 reviews

Excellent your people are Always very helpful and knowledgeable!

Thank You

Fast delivery and good price with discount. Please offer more incentives and I will always comeback. Great place to shop.


Ask a Question
  • I have a harman xxv pellet stove serial number 7233. I starts and works as it should except when I turn it off The flame goes off and goes into the cool down mode but the fan never shuts off. I will let it run for a couple hours unplug it and when I plug it back in the fan doesn't come back on. Do you think I need a esp probe or control board? Thanks

    The stove can take sometimes up to 30 to 45 minutes to shut down. The combustion blower will continue to work until the ESP probe no longer senses heat coming from embers still burning in burn pot.    If the stove's combustion blower is running after all embers are out it may be a false reading from the ESP probe. Make sure that the ESP probe is clean. Use a soft cloth so as not to scratch it. What happens from time to time is that build up of ash will get caked on probe. When the stove is running that build will get heated up and retain the heat longer. This ESP will sense the heat coming from that build up and shut down time will be extended. If after you have cleaned the ESP you still are having the problem then the ESP may be faulty and need to be replaced. If after replacing the ESP you are still having the problem then all signs point to the control board. 

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