Display shows E03 and charging stops immediately after relay click or does not start at all.

Safety first: Isolate the charger from mains supply and verify lockout/tagout before opening. High-voltage components are present.

• Listen for contactor operation: When starting a charge (before error), you should hear a distinct click from the internal contactor. No click or repeated clicking may indicate a faulty contactor or driver.
• Visual inspection (qualified person): Open the enclosure and locate the main power contactor. Check for discoloration, melted plastic, or signs of overheating on the contactor and surrounding wiring.
• Check terminal tightness: With power OFF, tighten all line, load, and control terminals on the contactor according to the torque specified by Mennekes. Loose connections can cause arcing and feedback errors.
• Contactor coil test: Measure coil resistance and compare with manufacturer data. If the coil is open or shorted, replace the contactor assembly.
• Feedback circuit: Many Mennekes chargers monitor contactor state via auxiliary contacts. Verify that auxiliary contacts are wired correctly and not mechanically stuck. Replace the contactor if auxiliary contacts are defective.

Note: If the contactor appears welded (output remains live when it should be off), the charger must be taken out of service immediately and the contactor replaced.