E900 — Control Board Communication Failure
Bosch's official US oven/microwave error-code page documents only E11 (touch keys/condensation) plus generic 'E and a number' catch-alls that instruct disconnecting power and calling Bosch support. A specific 'E900' is not separately documented. The 'control board communication failure' explanation below is not confirmed on Bosch's US consumer page — verify against your model's manual.
- Keep using it?
- Limited use only
- DIY difficulty
- Moderate
- Verified against
- bosch-home.com ↗
How to fix it
- Power off at the breaker for 5 minutes and retry — clears soft comm faults.
- Remove the top trim/control housing and reseat the ribbon cable at BOTH ends.
- Inspect the cable for kinks, scorch marks, or pinches.
- Swap in a known-good ribbon if available.
- If reseating fails, replace the UI board first (cheaper, more common failure).
- Replace the main control if E900 returns with a new UI.
Why it happens
Typical signs: Display lit but inputs ignored · E900 at power-up · Oven won't accept bake/broil commands · Intermittent display flicker
- Loose ribbon cable between UI and main control Heat cycling backs the connector out.
- Damaged ribbon cable Pinched or kinked at a service step.
- Failed user interface board Comm IC on UI no longer responds.
- Failed main control board Master end of the bus dead.
Parts you may need
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
More Bosch oven codes
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: bosch-home.com.