Not sure if it applies across models but
Error Code 84 - VSA sensor neutral position memorization
ServiceNews Article Feb 2008
Helping you fix it right the first time - every time
The VSA modulator-control unit can cause the VSA system indicators (ABS indicator, brake system
indicator, VSA indicator, and VSA activation indicator) to come on with VSA DTC 121-21 (VSA solenoid
valve malfunction: right-front and left-rear regulator valve).
If you get a vehicle in your shop with this problem, replace the VSA modulator (the control unit is a part of
this assembly). Refer to pages 19-169 and 19-170 of the ’05–07 Accord Hybrid S/M for instructions.
(Online, enter keywords VSA MODULATOR and select VSA Modulator-Control Unit Removal and
Installation from the list.) All replacement VSA modulators in Honda parts stock have been fixed for this
Make sure that you follow the removal and installation steps to the letter, especially the VSA sensor
neutral position memorization. If you don’t, you’ll wind up with DTC 84-21 (VSA sensor neutral position not