Breville BMO735 Sensor Cooking Used Worth It?

The Breville BMO735 is a 1.1 cu. ft. stainless steel microwave with “Sensor IQ” cooking, and as a used purchase it is worth it only if the sensor works reliably and you actually use automated programs. The sensor adds genuine convenience for reheating and defrosting, but it is the most failure-prone component in an older unit. This article explains how the sensor works, what to check before buying used, common problems, and how the BMO735 compares to simpler microwaves.

Formula

The calculator above estimates the actual cooking time when you reduce power from full. The formula is:

Adjusted time = sensor cook time × (power level / 10)

• t – the time the sensor program would use at full power (minutes).
• p – the power level you select (1 to 10, where 10 is full power).

This is a rough guide; actual time varies with food density, starting temperature, and container shape.

Worked Example

Using the defaults: sensor cook time = 3 minutes, power level = 7.

1. Divide power level by 10: 7 / 10 = 0.7
2. Multiply by sensor time: 3 × 0.7 = 2.1 minutes

So at power level 7, the adjusted time is 2.1 minutes (2 minutes 6 seconds). The calculator shows 2.10.

How Sensor IQ Works in the BMO735

The BMO735 uses a humidity sensor inside the microwave cavity. When you choose a sensor program (like reheat, baked potato, or vegetables), the microwave runs at full power and measures the moisture released by the food. When the rate of humidity change reaches a pre-set threshold, the microwave stops automatically. This is why you must not open the door during a sensor cycle—the sensor needs a sealed environment.

The key limitation is that the sensor does not measure temperature. It only measures humidity. Dense foods like bread or cheese release little steam, so the sensor may undercook them. Conversely, very wet foods may trigger early shut-off. The manual recommends covering food with a microwave-safe lid or vented wrap to direct steam toward the sensor.

What to Check Before Buying Used

Used BMO735 units are often 5–10 years old. The sensor is the first thing to fail. Before you buy, ask the seller for a live demo or at least a clear photo of the control panel. Test these specific things:

• Sensor reheat with a cup of water – it should stop within 2–4 minutes and not boil over.
• Door seal – any gap or worn gasket means steam escapes, confusing the sensor.
• Turntable rotation – uneven heating is often a stuck turntable motor.
• Control panel buttons – the membrane buttons on this model are known to become unresponsive after heavy use.
• Interior cleanliness – burnt food residue can cause false humidity readings.

If the sensor fails, replacement parts are scarce. Breville does not officially sell the sensor separately to consumers, and third-party parts are rarely available. A used unit with a dead sensor is essentially a manual microwave.

Common Problems and Misconceptions

The most common complaint is that sensor cooking undercooks or overcooks food. This is usually not a hardware fault but a misuse issue. Common mistakes include:

• Opening the door mid-cycle to stir or check – this resets the sensor logic.
• Using non-microwave-safe containers that absorb moisture or block steam.
• Placing food in a deep bowl instead of a shallow dish – steam collects unevenly.
• Not covering food – the manual explicitly says to cover for most sensor programs.

A misconception is that the sensor can detect “doneness” like a meat thermometer. It cannot. It only detects steam. For dense proteins, a probe thermometer is still the only reliable way to ensure safe internal temperature (e.g., 165°F / 74°C for poultry, 145°F / 63°C for whole cuts of meat).

Comparing the BMO735 to Other Microwaves

Compared to a basic 700W microwave, the BMO735 offers:

• Sensor programs for reheat, defrost, and vegetables – these genuinely save time if you reheat often.
• Variable power levels – more control for melting chocolate or softening butter.
• Stainless steel cavity – easier to clean, but heavier.
• Child lock and mute options – standard on most mid-range models.

However, newer budget microwaves (like a 2020s 900W unit) often have better evenness and faster heating due to improved inverter technology. The BMO735’s 1100W output is strong, but the sensor is the only real differentiator. If you rarely use auto programs, a simpler microwave will serve you just as well.

Costs and Reliability of a Used Unit

Used BMO735 prices vary widely by region and condition. Expect to pay roughly 30–50% of the original retail price. The main cost risk is sensor failure. If the sensor dies, you are left with a manual microwave that is heavier and bulkier than a new budget model. The magnetron (the component that generates microwaves) typically lasts 2000–3000 hours of use, so a used unit may have significant life left if it was lightly used.

Check the serial number and ask about the purchase date. Breville’s warranty is typically 1 year parts and labor, but that has long expired on most used units. No extended warranty will cover a used purchase from a private seller.

Safety and Practical Tips for Sensor Cooking

When using sensor programs, follow these safety points:

• Always use microwave-safe containers – no metal, no non-microwave plastic.
• Cover food with a vented lid or microwave-safe wrap to direct steam.
• Let food stand for 2–3 minutes after the sensor stops – the temperature continues to equalize.
• For reheating leftovers, ensure the food reaches 165°F (74°C) throughout. Use a food thermometer; the sensor does not guarantee this.
• Do not run the microwave empty – the sensor may misread and the magnetron can overheat.

If you buy used, clean the interior thoroughly before first use. Wipe the sensor window (usually a small rectangular area on the right side of the cavity) with a damp cloth – do not use abrasive cleaners.

Frequently Asked Questions

Can I replace the sensor in the BMO735 myself?

In most cases, no. The sensor is a proprietary part soldered to the control board. Breville does not sell it as a standalone part to consumers. Some repair shops may have salvaged parts, but labor costs often exceed the value of a used microwave.

Why does my sensor reheat stop too early?

The most common cause is that the food is not covered, so steam escapes before reaching the sensor. Also, if the food is already warm, the sensor detects moisture faster. Try covering the dish and starting with food at room temperature for consistent results.

Is the BMO735 safe to use if the sensor is broken?

Yes. The microwave will still operate in manual mode. The sensor only affects the auto programs. As long as the door seals properly and the magnetron works, it is safe. Just be aware that manual operation requires you to set time and power yourself.

How long does a Breville microwave typically last?

With normal use, a microwave magnetron lasts about 2000–3000 hours. That translates to roughly 5–10 years for an average household. A used BMO735 that is 8 years old may have limited life left, so factor that into the price.

Does the sensor work for defrosting meat?

The BMO735 has a sensor defrost program that measures moisture to adjust time. However, it is not precise for thick cuts. Always check that meat is fully thawed and cook immediately. Never refreeze meat that has been defrosted in a microwave.

What is the difference between Sensor IQ and regular auto-cook?

Regular auto-cook uses fixed time and power based on food type and weight. Sensor IQ measures humidity in real time and adjusts the cooking time automatically. This means it can compensate for variations in food size and starting temperature, but it cannot detect doneness.

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in t | Sensor cook time (min) | min | 3 | 0 | 30
in p | Power level (1-10) | - | 7 | 1 | 10
out adj | Adjusted time (min) | min | t * (p / 10) | 2