1. Connect the WDS or equivalent to the DLC-2.
2. Measure the PID value.
Note
PID/DATA MONITOR AND RECORD function table

Dtc p0841
TroubleshootingMazda 6 Service Manual: Power Steering
Power steering is only operable when the engine is running. If the engine
is off or if the power steering system is inoperable, you can still steer, but
it requires more physical effort. If the steering feels stiffer than usual
during normal driving or the steering vibrates, consult an A ...
Mazda 6 Service Manual: Control system
L.H.D.
R.H.D.
...