Graco Reactor E-XP1 Troubleshooting Manual page 22

Reactor Error Code Trouble Shooting Guide
3) Checking for a E21 error
o Check transducer A connection at J3, (E-20/E-XP1, H-series) or J5, (E-30/E-XP2)
on motor control board.
o Clean the plug and socket of transducer connection by unplugging and spraying
commercially available contact cleaner and reconnecting.
o Reverse A and B transducer connections. If error moves to transducer B (E22),
replace the transducer A. If error does not move then replace the motor control
board.
Rev 2.6 (02/2014) Page 22