GE "open steam sensor service may be needed"?

jvm7195ek2es model

when i use reheat feature unit stops prematurely with a solid beep then "open steam sensor service may be needed" appears in display. i have replaced the steam sensor (part WB24X799) but the same problem occurs and the same message is displayed using reheat feature. what other part needs to be replaced?
TomG, February 2020