Oven No-Bake: Test Igniter vs Valve vs Sensor First

Why this matters

A gas oven that will not bake fails on one of three things: a weak igniter that never opens the safety valve, a gas valve that will not pass fuel, or a temperature sensor/control that never calls for heat (or shuts it off early). They look identical from the door (cold oven, no flame) but resolve to very different parts. On an electric oven the same logic maps to element, relay, and sensor. Testing in the wrong order risks condemning an expensive gas valve when a cheap, common igniter was weak, and any guesswork around a live gas circuit is a safety exposure. A current-based test order settles most no-bake calls fast and safely.

Symptom presentation

A gas oven that glows at the igniter but never lights, or lights very late, is the classic weak-igniter pattern. An igniter that glows bright and the valve that still never opens points at the valve (or at insufficient igniter current to trip the bimetal in the valve). No glow at all points at an open igniter, a tripped thermal fuse, or a control that is not calling for heat. An oven that lights, heats, then quits well below setpoint points at the sensor/control branch. On electric units, no glow from the bake element with the control calling heat parallels the gas igniter branch.

The most common real-world version is the slow-degrading igniter. As a silicon-carbide igniter ages, its resistance rises and the current it draws falls; for months the oven still lights, just a little later each time, until one day the current drops below the threshold the safety valve needs and the oven goes cold. Because the igniter still glows, customers and even techs assume it is fine and chase the valve or control. Measuring igniter current, not just watching it glow, is what catches this and prevents a wrong valve replacement.

Quick checks

• Confirm gas supply is on and the broiler or surface burners light, which isolates a whole-appliance gas problem from a bake-circuit-only problem.
• Set bake and watch the igniter through the burner port. A dim orange glow that never lights, or lights only after a long delay, is a weak igniter; a bright white-orange glow that lights promptly is healthy.
• On electric, watch the bake element for an even orange glow; cold spots or no glow point at an open element or a blown bake relay.
• Confirm the control panel shows the bake call active and the range is not in a delay-start, control-lock, or Sabbath/demo mode that suppresses heat.
• Verify 120V (or 240V across both legs on an electric range) at the appliance terminal block.
• Listen for the safety valve: on a healthy gas oven you hear a soft click and gas flow shortly after the igniter reaches full glow.

Isolation tree

On gas, current through the igniter is the master test, because the igniter is wired in series with the safety valve and must draw enough current to open it.

1. Igniter branch (gas): Clamp an ammeter on the igniter leg. A bake igniter typically must draw roughly 3.2 to 3.6 amps to open the valve; a glowing igniter pulling only 2 to 3 amps is weak and will not open the valve even though it looks lit. Replace the igniter on low current. No current with the control calling heat points upstream (thermal fuse, control, wiring).
2. Valve branch (gas): If the igniter draws full rated current and stays hot but no gas flows, the safety valve bimetal or solenoid has failed. Confirm the igniter current first, then condemn the valve only when current is in spec and gas still does not open.
3. Element branch (electric): Ohm the bake element (typically 15 to 40 ohms; infinite is open) and confirm 240V across its terminals when bake is called. An open element or a failed bake relay on the control gives no heat.
4. Sensor/control branch: If the oven heats but misbehaves on temperature, measure the oven temperature sensor (RTD-style sensors read about 1080 to 1100 ohms at room temperature and rise with heat). An out-of-range sensor makes the control under- or over-shoot, or quit early. A good sensor with bad regulation points at the control board.

Confirming diagnosis

The igniter is confirmed faulty when it glows but draws below the valve-opening threshold; replacing it restores ignition. The valve is confirmed only when igniter current is verified in spec and gas still will not flow. On electric, an element that ohms open or shows no 240V across its terminals during a bake call confirms the heat-source branch. The sensor is confirmed by a resistance reading outside its room-temperature spec, or by an oven that tracks far from setpoint with a good element/igniter. Recheck calibrated oven temperature after any repair.

Remediation

• Igniter: Replace a weak or open igniter (handle the silicon-carbide or flat-ribbon element only by its bracket; skin oils create hot spots that shorten its life). Verify the new igniter draws full rated current and the valve opens.
• Valve: Replace the gas safety valve only when igniter current is confirmed in spec and gas still will not open. Leak-check every joint with the gas restored on restart.
• Element: Replace an open bake element or a failed bake relay on the control board; confirm 240V across the element terminals during a bake call after replacement.
• Sensor/control: Replace an out-of-range temperature sensor (RTD reading off its ~1080 ohm room-temperature spec); replace the control board only when a verified-good sensor still yields bad temperature regulation.

References

• ANSI Z21.1 / CSA 1.1, Household Cooking Gas Appliances
• UL 858, Standard for Household Electric Ranges
• NFPA 54, National Fuel Gas Code
• DOE, 10 CFR Part 430, Subpart B (energy conservation test procedures, kitchen ranges and ovens)