E9 — Safety Temperature Limiter (STB) tripped

What does E9 mean?

The Safety Temperature Limiter (STB) has activated, indicating that a critical temperature limit has been reached or exceeded within the boiler. This is a safety shutdown.

• The STB has tripped due to excessive heat in the system.
• The exhaust gas NTC sensor or its connection cable is faulty.
• A malfunction in the TA 211 E or RAM unit, or the main circuit board.

Click steps to track your progress.

1. 1

   Check the exhaust gas NTC sensor and its connection cable for any damage or disconnections. Replace if necessary.

2. 2

   Inspect the TA 211 E or RAM unit for any signs of malfunction or connection issues.

3. 3

   Examine the main circuit board for any visible damage or signs of error.

4. 4

   If the STB continues to trip, contact customer service for further diagnostics and professional assistance.