Thermador Oven Over-Temperature Lockout (Runaway Heat Protection)

What Over-Temp Lockout means

Thermador ovens watch the cavity temperature with the RTD sensor and will trip a protective lockout if temperature exceeds the firmware limit, especially during the high heat of self-clean. The lockout opens the heating circuit so the oven cannot keep climbing. The exact displayed code varies by model and generation, so the precise fault number must be confirmed against the model and manual, but the meaning is consistent: the oven got too hot and the control intervened.

Common causes

• Heating element relay welded closed, keeping an element energized
• Oven temperature sensor reading falsely low, causing overheating
• Failed thermal limit or door-lock thermostat
• Self-clean cycle overshoot from a marginal control or sensor
• Control board fault driving the elements past the limit

Why Over-Temp Lockout happens

The most serious cause is a bake or broil relay on the power board that has welded shut, leaving an element powered even when the control commands it off. A sensor reading falsely low makes the control overdrive the elements. A stuck or failed thermal limit/door-lock thermostat and self-clean overshoot are also contributors.

What you'll typically see

• Oven shuts down and displays an over-temperature or runaway-heat message
• Oven became far hotter than the set temperature before cutting out
• Lockout most often triggers during or right after self-clean
• Burning smell or smoke from the cavity
• Oven refuses to restart until the fault is cleared and the cause repaired

Parts involved in Over-Temp Lockout

• Relay / power board — Replaced when a bake or broil relay has welded closed and keeps an element on
• Oven temperature sensor (RTD probe) — Replaced when it reads falsely low and lets the oven overheat
• Thermal limit / door-lock thermostat — Replaced when the high-limit safety device has failed

What you can check yourself

• Turn the oven off at the breaker immediately if it is still hot or smoking, and let it cool fully
• Do not attempt to restart self-clean until the cause is diagnosed
• Keep the oven door closed while the cavity cools to avoid releasing heat into the room
• Note what cycle was running when the lockout occurred and report it to the technician

When to book a pro

An over-temperature lockout can mean an element is being powered by a welded relay, a genuine safety issue that requires measuring the relay board, testing the sensor and limit thermostat, and replacing the failed part under line voltage. This should not be reset and reused without diagnosis.