Tech Tip - E31 Error Code

Posted By DEMILEC || 2-Apr-2011

On Reactor E-Series Graco machines: An error code not commonly found in manuals is E31. This means the motor switch on the control board has shorted out and you need to replace the motor control board.

Below are the steps to trouble shoot an error code E31:

  1. 1.) Remove machine from the power source.
  1. 2.) Thoroughly check the drive motor by removing the top motor brush and rotating the motor manually with the internal fan blade.
  1. 3.) Inspect the motor commutator all the way around for any evidence of burning or pocking.
  2. 4.) Continue to rotate the motor until you have completed one pump cycle, up and down to insure there is no mechanical interference in pump lower or gear drive system.

Note: The Reactor machines that have the large blue capacitor will have to have it verified for proper function as well.

If after confirming a good motor and a capacitor, and confirming the input power source is at the required voltage and phase, you will need to replace the motor control board.

As always read, understand and follow all instruction manuals and warning labels supplied with all equipment. Only trained and qualified personnel should perform repairs on the equipment. To access the latest equipment manuals visit

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