- Appliances
- Microwave ovens
E21
Whirlpool E21 on a microwave: thermal sensor circuit open
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On a Whirlpool over-the-range microwave, E21 means the thermal sensor circuit reported open to the control board. Whirlpool says to switch the breaker off for one minute, back on, watch for one minute and test operation.
Safety first
Stop and check this first
- An over-the-range microwave is not taken apart to check boards or wires: the high voltage capacitor can keep a lethal charge even with the power off. Magnetron, door seals and safety interlocks are for authorised service only.
Safe checks you can perform
- Code reading and timing
- Breaker off for one minute
- Operating test with a load
Leave these tasks to a qualified professional
- Do not attempt this professional task: Thermal sensor circuit measurement
- Do not attempt this professional task: Load test after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Thermal sensor circuit measurement
What they doThe authorised technician measures the thermal sensor and the continuity of its wiring to the board against the service manual values, after discharging high voltage.
They must show youthe sensor value and the wire continuity test against the specification.
In writingwhere the break was and the replaced part with its part number.
Load test after the repair
What they doThe technician runs a cycle with a load and checks the code does not return.
They must show youthe full cycle without E21.
In writingthe test, the result and the date.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Code reading and timing
- Who:
- you, no tools.
- How:
- confirm it shows E21 and note whether it appeared at power-up, at rest or while cooking.
- Result that matters:
- the exact code and when it appears.
- If it appeared at rest or at power-up:
- it points to a fixed break; note it.
- If only while cooking:
- note it; it may be a connection that fails with heat.
- Evidence to keep:
- photo of the display and a note of the timing.
Evidence: E21 - Error Code - Over-the-Range Microwave
Breaker off for one minute
- Who:
- you, at the breaker panel and without opening the unit.
- How:
- switch the microwave's breaker or breakers off for one minute, switch them back on and watch the display for another minute, as Whirlpool says.
- Result that matters:
- whether E21 reappears within that minute.
- If it does not return:
- test operation with a load.
- If it returns:
- the circuit is still open; call Whirlpool service.
- Evidence to keep:
- time of the cut and whether the code came back during the minute.
Evidence: E21 - Error Code - Over-the-Range Microwave
Operating test with a load
- Who:
- you, with a microwave-safe container of water.
- How:
- place a microwave-safe container of water inside and set a short time, watching it. Do not run it empty.
- Result that matters:
- that the cycle ends without E21.
- If it ends:
- solved; watch for a repeat.
- If E21 returns:
- ask for service.
- Evidence to keep:
- note of the result.
Evidence: E21 - Error Code - Over-the-Range Microwave
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Appliances
- Brand
- Whirlpool
- Product type
- Microwave ovens
Known code variants
- Bosch dishwasher E21
- Bosch E21
- Bosch E21 error
- Bosch Geschirrspüler Fehler E21
- E21
- E21 Bosch dishwasher
- E21 lavavajillas Bosch
- E:21
- error E21 Bosch
- error E21 lavadora Teka
- error E21 lavavajillas Haier
- F21
- F:21
- Fehlercode E21 Bosch
- Haier dishwasher E21
- Haier dishwasher error E21
- Haier dishwasher solenoid valve open E21
- Haier dishwasher water keeps filling
- Haier lavavajillas E21
- lavadora Teka TKD E21 no desagua
- lavavajillas Bosch E21
- lavavajillas Haier electroválvula abierta E21
- lavavajillas Haier entra agua sin parar
- microondas Whirlpool E21 sensor térmico
- Teka E21 error washer
- Teka E21 lavadora
- Teka TKD washer E21 not draining
- Teka washing machine E21
- Whirlpool E21 over the range
- Whirlpool microondas E21
- Whirlpool microwave E21
- Whirlpool microwave E21 thermal sensor
- Whirlpool over the range E21
What it means
Whirlpool defines E21 like this: the thermal sensor circuit reported open to the control board. There may be a problem with the thermal sensor, the appliance control board or the associated wiring. An open circuit means the board gets no signal from the sensor, as if it were disconnected. The code does not say at which of the three points the break is, so on its own it does not prove the sensor is faulty. The page is Whirlpool US's over-the-range microwave guide; confirm the code in your model's manual.
Warnings and stop conditions
- Higheditorial warning
An over-the-range microwave is not taken apart to check boards or wires: the high voltage capacitor can keep a lethal charge even with the power off. Magnetron, door seals and safety interlocks are for authorised service only.
Evidence: E21 - Error Code - Over-the-Range Microwave
Symptoms and causes
Probable causes · in order
- Thermal sensor openPossible
Whirlpool cites it first. It fits if E21 returns as soon as power is back, even without using the unit.
Evidence: E21 - Error Code - Over-the-Range Microwave
- Loose wire or connectorPossible
A broken wire or a dislodged connector gives the same open circuit. Only the technician can tell it from the sensor.
Evidence: E21 - Error Code - Over-the-Range Microwave
- Control boardLess common
Whirlpool includes it too. It is considered when sensor and wire measure fine and the code persists.
Evidence: E21 - Error Code - Over-the-Range Microwave
Virtual technician
Does E21 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
E21 - Error Code - Over-the-Range Microwave
Whirlpool · 2026 · official_doc
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