Bosch Washer Error Code E43 — How to Fix It

What Does This Error Mean?

Bosch washer E43 means the main control board (PCB) has detected an internal fault or lost communication with a sub-module. Power cycle the machine first: switch off at the wall for 5 minutes, then switch back on — transient PCB faults often clear on a full power reset. If E43 returns immediately, the control board has failed and needs replacing.

Affected Models

Bosch Series 2 Washer
Bosch Series 4 Washer
Bosch Series 6 Washer
Bosch Series 8 Washer
Bosch i-DOS Washer
Bosch WAU Series

Common Causes

Mains power surge damaged the control board during a storm or power cut
Capacitor on the control board failed — common after 7–10 years of use
Water ingress into the control board housing from a detergent drawer overflow
Wiring harness connector on the control board become loose after vibration
Internal communication bus failure between the main board and motor or sensor module

How to Fix It

Power cycle the washing machine

Turn off the machine at the wall socket and leave it off for at least 5 minutes. This discharges residual voltage from the control board capacitors and can clear a transient fault. Switch back on and see if E43 returns.
Check for water damage

If the detergent drawer has been overfilled or has leaked, water can enter the control module area (usually behind the front panel at the top). Inspect for moisture or white water marks around the control board housing.
Check wiring harness connectors

After removing the top panel, check each wiring harness connector on the main PCB is fully seated. A connector that has worked loose from vibration causes intermittent E43.
Run a diagnostic cycle

On many Bosch washers, holding the Spin and Temperature buttons simultaneously for 3 seconds starts a self-diagnostic. The error code confirmed during diagnostic helps identify which board function has failed.
Replace the control board

Order the control board for your specific model (printed on the rating plate inside the door frame). Remove the top panel, disconnect all wiring harnesses from the old board, unscrew it, and fit the new board. Cost is typically $80–180.

When to Call a Professional

E43 almost always requires a control board replacement. Correct installation may require recalibrating motor parameters on some models — Bosch-certified service is recommended if you are not confident with PCB replacement.

Frequently Asked Questions

Can Bosch washer E43 be caused by a power cut?

Yes — a sudden power cut during a wash cycle can corrupt the control board's operating state. Always try a full power cycle first after a power cut before assuming the board has failed.

My Bosch washer shows E43 but programmes still start — what does it mean?

If programmes start but E43 appears during a specific phase, the board is failing under load rather than at startup. This is a sign of a failing capacitor on the board — replacing the board will resolve it.

Is it worth replacing the control board on an old Bosch washer?

If the washer is under 8 years old and otherwise in good condition, a control board replacement makes sense. For machines over 10 years old, compare the board cost ($80–180) against the cost of a new machine.