What Er:03 Means
Er:03 is the opposite of the stuck-lock fault: the Bosch washer asked the door lock to engage at the start of a cycle and it did not. The service table gives the same two causes, a jammed lock or a bad wire harness. Because the machine will not fill until the door is confirmed locked, the practical symptom is a washer that accepts a programme and then does nothing.
Common Causes of Er:03
- Lock mechanism jammed by residue or a broken internal part
- Wire harness to the lock damaged where it passes the hinge area
- Striker or latch tongue worn so the lock cannot engage
🔧 One Safe Check You Can Try
Check the latch tongue on the door and the striker in the frame for lint, hair and detergent residue, and clean them with a dry brush. Then close the door with a firm, deliberate push rather than a swing, which is often all a worn latch needs.
⚠ Why You Shouldn't Go Further Than That
- A washer that cannot lock its door will not fill, so there is no way to test any repair without completing it first.
- The lock sits behind the front panel with the door seal retaining ring over it, and that ring has to come off and go back correctly.
- Bosch names the harness alongside the lock itself, and the harness runs where the door movement flexes it every cycle.
- Defeating the lock circuit to make the machine run removes the interlock that keeps a spinning drum shut.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.