We present high-resolution observations of the 12CO J = 3-2 emission associated with HH102 in the L1551 molecular outflow. At low and intermediate blue-shifted velocities the emission is found in a shell which coincides with the optical reflection nebulosity from HH102. In places, the shell appears to be unresolved, implying a width of less than ~ 0.01 pc. Within the shell several bright clumps can be identified. By combining the J = 3-2 data with previous J = 1-0 maps, we derive excitation temperatures and beam-filling factors for these clumps. The gas is found to be hot (up to ~ 40 K) and often has low filling factor (~ 0.2). We compare the distribution of the CO emission with those of the optical reflection nebulosity and the Hα shocked emission. The data are consistent with a fast wind from IRS5 being shocked immediately in front of the boundary between the wind-eroded cavity and the swept-up molecular gas. We suggest that the particularly energetic activity in the vicinity of HH102 is a result of the direct impact of material in a fast, collimated jet such as those traced by the radio jets emanating from IRS5. If so, previous interpretations of the presence of both red- and blue-shifted CO around HH102 may be incorrect. In particular, the data need not be explained as solely due to the presence of a slow rotation of the outflow about its axis
