Probable Causes:

Open in ECT 1 circuit for 2 seconds or more (Code 81).
Open in ESA 1 circuit for .5 seconds after .5 seconds at idle (Code 83).
Open in ESA 2 circuit for .5 seconds after .5 seconds at idle (Code 84).
Open in ESA 3 circuit for .5 seconds after .5 seconds at idle (Code 85).

NOTE: Diagnostic chart is not available from manufacturer.