Note On Intermittents:

If only Code B337 shows up as "History", check for momentary opens in circuits No. 800F and 800E, or momentary loss of both ignition 3 (circuit No. 750), or momentary loss of ground (circuit No. 801M).

If Code B337 is set as "History", along with any of the following codes set as "History"; B334, B335, B336, B552, B553 and/or EO47, see MULTIPLE INTERMITTENT CODES  chart.

Fig 1: Code B337, Loss of HVAC Programmer Data (Riviera)

Fig 2: Code B337, Schematic