Bosch Oven Running Too Hot

Most Likely Cause#

When a Bosch oven runs hot, it is almost always either the temperature sensor reading low or the element relay stuck closed — and those two are very different in seriousness. A drifting NTC sensor that reads cooler than reality makes the board keep heating, and it is the most common cause at about 40%. A control-board relay welded shut, which keeps the element energized no matter what, is next at about 35% and is the dangerous one. A failed convection fan creating hot spots at about 15% and simply using the wrong mode at about 10% round it out.

Symptom-to-Cause Table#

How Bosch Regulates Temperature#

The board reads an NTC temperature sensor continuously and switches the element on and off through a relay to hold the setpoint. Overheating means one of two things has broken that loop: either the sensor is reporting a temperature lower than reality, so the board keeps calling for heat, or the relay has welded closed, so the element never shuts off even when the oven is already hot. The first bakes consistently hot; the second climbs without stopping, and that distinction drives everything below.

Safety First#

An oven whose element never cycles off is a genuine fire hazard — it will keep climbing until the thermal fuse blows, and if that fuse has been bypassed there is nothing left to stop it. If your Bosch is running far over the setpoint (on the order of 75F above target) and the element glows continuously without ever fading, turn it off at the breaker and stop using it until the relay is repaired. A slight overrun is a nuisance; a non-cycling element is not.

The Causes in Detail#

The NTC sensor drifts most often: as it ages its resistance shifts, and reading high resistance the board interprets as a cool oven and overheats to compensate — at room temperature a healthy sensor reads roughly 1,050 to 1,100 ohms, and a drifted one reads higher. A relay welded closed is the serious fault, keeping the element on continuously; that is a board repair, not a calibration. A dead convection fan lets the rear ring element bake its immediate area while the rest of the cavity lags, so the center reads normal but the back scorches. And many too-hot complaints are simply mode confusion — Broil or convection at the same number bakes hotter, and Bosch even suggests dropping the set temperature by 25F when switching to convection.

How to Narrow It Down#

1. Put an oven thermometer in the center, set 350F, and after about thirty minutes read the actual temperature.
2. Watch the element after preheat: it should fade off and back on; if it stays continuously bright, the relay is stuck.
3. Confirm the mode shows Bake, not Broil or convection, before assuming a fault.
4. Measure the sensor at room temperature — well above about 1,100 ohms means it has drifted.
5. If the oven overshoots by around 25F, use the calibration offset in settings (up to roughly 35F); a 50F-plus overshoot means the sensor or relay, not calibration.

Repair or Replace?#

A calibration tweak or a sensor swap is inexpensive on an otherwise sound Bosch, and even a convection fan is a bounded part — so most overheating ovens are worth fixing. The control board behind a stuck relay is the priciest case, and while it is a bigger outlay it still beats replacing a good oven. The relay case is the one not to defer, purely for safety. EasyBear can measure the sensor, watch the element cycle, and repair it in one visit — book now.

Prevent It Coming Back#

• Check your real oven temperature with a thermometer now and then, especially if baking results drift.
• Use the calibration offset for small, steady overruns rather than living with them.
• Drop the set temperature by about 25F whenever you switch to convection.
• If the element ever stops cycling off, treat it as urgent and cut power at the breaker.