Bobcat S150 04-21 Error Code
04-21 Error Code
Engine Oil Pressure Out Of Range High is the main cause of 04-21 error.The condenser converts gases into liquids, which expels heat from your rig. Materials can build up over time, causing a layer of dirt and grime to form on the condenser's coils. Your AC system will only blow hot air since the refrigerant fails to cool down.

Tip For S150 Model
When a WARNING condition exists; the associated icon
light is ON and the alarm sounds 3 beeps. If this
condition is allowed to continue, there may be damage to
the engine or hydraulic systems.
When a SHUTDOWN condition exists; the associated
icon light is ON and the alarm sounds continuously. The
monitoring system will automatically stop the engine in
15 seconds. The engine can be restarted to move or
relocate the excavator.
The SHUTDOWN feature is associated with the following
icons:
General Warning
Engine Malfunction
Engine Coolant Temperature