The oven’s on, the light’s on, and the inside is cold. An oven not heating up is usually a setting, a breaker or one worn part, and the first two cost nothing to check. In our experience the common no-parts causes are a wrong setting, a delayed start or a demo mode. A breaker that’s only partly tripped comes next. Past those, the fault is an igniter, a temperature sensor or an element, and each has a measured test.

Before you touch anything inside the oven, switch its power off at the breaker and let it cool. If you ever smell gas, stop and call us.

Two Questions First: Gas or Electric, and How Much Heat

Two answers cut the list of suspects in half before you pick up a tool. Is the range gas or electric? And is there no heat at all, or only weak heat?

A gas oven runs on ordinary 120 V. An electric oven needs 240 V to heat. So a gas oven with a dead display and no lights has an electrical or control fault, not a gas supply problem.

On an electric range, working lights prove less than you’d think. A partly tripped double-pole 240 V breaker leaves one live leg feeding the clock, the lights and the surface burners, while the oven gets no heat at all.

Which mode is dead matters too. If bake is dead but broil works, or the reverse, the fault is a single element on an electric oven or a single burner tube on a gas oven. It isn’t the supply feeding the whole oven.

Weak or uneven heat is a different case. That’s where the temperature sensor comes in, further down.

Free Fixes for an Oven That Won’t Heat

Start here, because a meaningful share of these calls end here. Door-latch problems turn up less often and depend more on the model, so they come last.

1. Look at the display for a timer, cook time or delay-start indicator. A delayed start leaves the oven doing nothing until the programmed time. Clear it and set bake again.
2. Check the mode is Bake and the temperature is actually set. Check the knob position on a dial model.
3. Look for demo mode. If the display and keypad respond but nothing heats, find your model’s exit sequence in the owner’s manual.
4. On an electric range, look at the double-pole breaker. If either half is tripped, the clock and lights can work while the oven stays cold. Switch it fully off and back on once. If it trips again, stop and call.

Demo mode is real. Whirlpool, GE and Samsung all document showroom modes on their ranges. On a Whirlpool the owner can often clear it from the control panel, but the button sequence depends on the model. Some Samsung ranges have a demo-mode setting you can turn off from the keypad.

Some GE models drop into demo mode because they’re getting 120 V instead of the 240 V they need. That one isn’t a setting. It’s an electrical connection, and checking it is not a homeowner job.

Gas Ovens: Checking an Igniter That Glows but Won’t Light the Burner

A common gas complaint: the igniter glows orange, the burner never lights and the oven stays cold. A glowing igniter isn’t a working igniter.

The oven’s safety valve opens on the current drawn through the igniter circuit. It doesn’t sense heat or flame. So an igniter can glow brightly and still pass too little current to open the valve.

A resistance reading, roughly 80 to 180 ohms, only proves the igniter isn’t open-circuit. It can’t catch a weak igniter that still glows. For that you need a clamp-on ammeter reading the actual current draw while the circuit is live.

If you don’t own one, this is where your testing ends and oven repair begins. If it’s the cooktop burners that won’t light, that’s a different ignition system, covered in the post on a stove that won’t light.

Testing the Temperature Sensor When Heat Is Weak or Erratic

Switch the breaker off and let the oven cool first. The sensor is held to the rear oven liner by two screws.

1. Disconnect the sensor and measure resistance across the two prongs of its connector.
2. Compare it to the published figure for the common sensor type. It should read about 1080 to 1090 ohms at room temperature, roughly 21°C (70°F). A reading far from that condemns the sensor. Your manual has the figure for your model.
3. Warm the probe with a hair dryer and watch the reading. Resistance rises with temperature at about 2 ohms per °F, or roughly 3.6 ohms per °C. On the published curve that’s about 1453 ohms at 121°C (250°F) and 1852 ohms at 232°C (450°F). A steady, proportional climb is a healthy sensor.
4. To separate a failed sensor from failed wiring, measure at the control board connection, then directly at the disconnected sensor. If both readings match, the wiring isn’t at fault.

A sensor that reads right cold but climbs oddly or not at all is the one a cold reading alone would miss.

Electric Ovens: Testing the Bake and Broil Elements

A failed oven element doesn’t always look failed. There may be no burning, no blistering and no visible break. We’ve seen elements look perfect and still be dead.

Switch the breaker off and let the oven cool. Then:

1. Photograph the terminal positions so you can reconnect everything correctly.
2. Disconnect at least one lead from the element. Measured in place, the meter reads parallel paths through the rest of the oven’s wiring, not the element alone.
3. Measure resistance across the element terminals.
4. Read the result against the element’s own rating, not a universal range. Resistance works out as volts squared divided by watts. On 240 V, a 2500 W element comes to roughly 23 ohms, a 2000 W element about 29 ohms and a 1500 W element about 38 ohms.

A reading of OL, or infinite resistance, means the element is open and has failed. A reading at or near 0 ohms means a short, which is the rarer of the two faults.

Passing cold doesn’t clear an element. A cold continuity test is useful, but an element can test fine cold and fail once it’s hot, usually from a connection that opens as the metal heats and expands. If the element passes and the oven still won’t heat, stop there.

Where to Stop and What a Repair Involves

You can do the free checks, look over the element, and take the resistance readings with the power off. Stop at any of these:

• A smell of gas.
• A GE range in demo mode that may be getting 120 V instead of 240 V.
• Anything at the breaker panel or the supply to the range, if the breaker trips again after one reset.
• A glowing gas igniter with a cold oven, since the current test needs a clamp-on ammeter on a live circuit.
• An element that tests fine cold while the oven still won’t heat.

On cost, published quotes put a gas igniter replacement at $150 to $325 installed, against a part that costs $20 to $50. Most of the gap is the labour of reaching and testing the ignition system. An electric element runs $150 to $450 installed against a $15 to $100 part. An oven has two elements, bake and broil, so the failed one has to be identified first.

When you book oven repair in Thornhill, tell us three things: gas or electric, no heat or weak heat, and which checks above you’ve already ruled out. That saves a step on the first visit. We also do dishwasher repair if another appliance gives you trouble.