Zoomlion Fault Code

Free · no signup

0x0421 / E0421

Crowd / Feed Cylinder Sags under Load

System

Mast / Winch

Symptom

Crowd / Feed Cylinder Sags under Load

Diagnosis & fix steps

LOGIC: Mast Crowd Pressure Proportional Relief Valve Output Feedback Error. ACTION: Measure internal coil resistance of crowd valve proportional solenoid. Test output current from the primary IFM mobile controller driver channel under load.

Red Seal field insights

Foundation Force: Prevents uncontrolled mast crowd cylinder movement or casing drive stalling during high-torque CFA and Kelly drilling operations.

Same code keeps coming back?

That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.

Book an uptime review

Read before you touch anything

  • This is general reference information, not a repair manual. It is for trained, qualified technicians.
  • Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
  • Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
  • You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
  • Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.

Track this across your whole fleet

This code is free to read. AM Fleet Integrity lets your team log fault codes against assets, plus the full fault-code library, QR operator reporting, PM scheduling and predictive alerts. Start free — no credit card required.

Start your free trial

Related Zoomlion fault codes

← All Zoomlion fault codes