The John Deere 6.8l and 8.1L CNG enignes using the OH1.2 system are supported by John Deere directly. For technical support contact Mike Dekutoski, DekutoskiMichaelB@JohnDeere.com or 319-292-6370, at John Deere. Also see https://www.deere.com/en_US/services_and_support/engine-information/natural_gas_engines_electronic_control_system/natural_gas_engines_electronic_control_system.page for more support from John Deere.
For more information about the OH1.2 system see Woodward product specification 03224.