Charger display shows E004 and will not energize the vehicle; often occurs immediately after plugging in.

Safety first: The main contactor switches high current. Only qualified personnel should open the unit. Isolate power at the breaker and lock out/tag out if possible.

• Power cycle: Turn off the charger at the breaker for at least 2 minutes, then restore power and check if E004 clears. If it returns immediately, proceed with inspection.
• Inspect contactor: With power OFF and cover removed, locate the main power contactor. Check for discoloration, melted plastic, or a burnt smell. Inspect wiring for tightness and signs of overheating.
• Mechanical test: Gently operate the contactor manually (if design allows) to ensure it moves freely. A stuck or welded contactor must be replaced, not repaired.
• Auxiliary contacts: Verify that the auxiliary feedback contacts are correctly wired to the main control board and that terminals are secure.

Because a welded contactor can pose a serious safety risk (live pins when not commanded), replacement of the contactor and verification of correct operation should be performed by a Siemens-authorized technician.