Audi wallbox displays E03 and charging stops or will not start; sometimes occurs intermittently during charging.

Safety first: Ground fault conditions can be hazardous. Do not continue to reset and use the charger without identifying the cause.

• Check for moisture: Inspect the Type 2 plug and vehicle inlet for water, condensation, or road salt. Dry thoroughly with a lint-free cloth and allow to air dry. Avoid using heat guns directly on plastic parts.
• Try another vehicle: If possible, connect a different Audi EV or another EV to determine whether the fault follows the vehicle or remains with the charger.
• Inspect cable and sheath: With power off, examine the entire length of the charging cable for cuts, abrasions, or crushed sections. If copper conductors are visible or the sheath is deeply damaged, replace the cable assembly.
• Reset the charger: Turn off the supply breaker for 5 minutes, then restore power. If E03 appears immediately without a vehicle connected, the internal residual current sensor or its electronics on the main board may be defective.
• Professional insulation test: An electrician should perform insulation resistance tests on the cable and internal wiring, and verify the operation of the integrated RCD / DC residual current sensor. Replace the RCD module or main control board if faulty.

Do not bypass or disable the ground fault protection. Replace damaged cables or faulty RCD components before further use.