Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionRocker Arm Removal
Squeeze the brake lever slowly and hold it with a band.
Remove the front footpeg bracket bolts.
Raise the rear wheel off the ground with the jack (see
Rear Shock Absorber Removal).
Special Tools - Jack: 57001-1238
Jack Attachment: 57001-1608
Remove:
Lower Rear Shock Absorber B ...
ESD (Electronic Steering Damper) ECU Error (Service Code E3b, ZX1000JD/KD)
If this service code appears, check that the following parts
are correctly.
Crankshaft Sensor
Gear Position Switch
Starter Lockout Switch
Main Throttle Sensor
Rear Wheel Rotation Sensor
If these parts are normal, check the ESD ECU for its
ground and power supply (see ESD ECU Power Supply
...
Rear Shock Absorber Scrapping
WARNINGPressurized nitrogen may explode when
heated.
The rear shock contains nitrogen gas. To avoid
an explosion, do not incinerate the shock body
without first releasing the nitrogen and removing
the shraeder valve.
Remove the rear shock absorber (see Rear Shock Ab ...