Bosch Washer Error Code E31 — What It Means & How to Fix It

What Does This Error Mean?

The E31 error on your Bosch washer means there is a communication failure between the motor control module and the main control board. These two electronic boards need to communicate constantly during a cycle. When that communication breaks down, the machine stops completely for safety.

Affected Models

Bosch 300 Series
Bosch 500 Series
Bosch 800 Series
Most Bosch front-load washers

Common Causes

The wiring harness between the motor module and main control board has come loose
A power surge has damaged one or both control boards
The motor control module has failed internally
The main control board has failed and can no longer communicate with the motor module
Corrosion or moisture has damaged the connectors between the two boards

How to Fix It

Unplug the washer from the wall. Leave it unpowered for at least five minutes.

A brief power reset sometimes clears a temporary communication error caused by a power spike.
Plug the machine back in and try running it again. If E31 clears and the machine operates normally, monitor it closely for recurrence.

If E31 returns quickly, a board has failed and needs replacement.
Check that the washer is plugged directly into a wall outlet — not a power strip or extension cord.

Voltage instability from extension cords or overloaded power strips can disrupt board-to-board communication.
Inspect the wiring harness connections at the back of the machine if you are comfortable doing so. Look for any unplugged or visibly damaged connectors.

Vibration over years of use can work internal connectors loose.
If the error persists after a reset, contact Bosch service or a qualified appliance technician. Board diagnostics and replacement are required.

Do not attempt to replace control boards yourself unless you have appliance repair experience.

When to Call a Professional

E31 almost always requires professional repair. Both the motor control module and main control board are expensive parts. A technician can test which board has failed before ordering parts. Expect $200–$500+ for this repair depending on which component has failed.

Frequently Asked Questions

Can a power outage cause E31?

Yes. A sudden power cut or power surge during a wash cycle can corrupt the communication between the two control boards. Try a full power reset first. If E31 persists, the surge may have damaged one of the boards permanently.

How do I know if the motor module or main board needs replacing?

A technician will use a diagnostic tool (or a process of elimination) to test both boards. Replacing the wrong board wastes money. Always get a proper diagnosis before ordering parts — main boards can cost $150–$300 and motor modules $100–$250.

Is it worth repairing a Bosch washer with E31?

It depends on the age of the machine. If your washer is under 10 years old, repairing it is usually cost-effective. If it is over 12–15 years old and the repair costs more than half the price of a new machine, replacing it may make more sense.