What E309 Means
E309 is the control module's version of the program memory check failure. Bosch pairs it on the same table row with the user interface code, and the distinction is which board is replaced: the interface for the E009 form, the control module for E309. The consequence is identical, all heating elements are disabled, and the error cancels at start-up if the next memory check passes.
Common Causes of E309
- Program memory on the control module corrupted
- Power interruption during a memory operation
- Control module reaching the end of its service life
🔧 One Safe Check You Can Try
Cut power at the breaker for two minutes and let the oven run its start-up check again. One clean start after a power event is not unusual; a code that comes straight back is the board telling you the check genuinely failed.
⚠ Why You Shouldn't Go Further Than That
- The distinction between this code and its interface counterpart decides which of two boards gets bought, and they are not interchangeable.
- The control module sits in the plenum above the cavity, reached by removing an access panel after the oven is drawn out.
- Control modules carry an option code specific to your model, and a replacement fitted without setting it produces a different fault immediately.
- Every heating element is disabled while this is active, so there is no way to test progress until the work is complete.
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.