In one paragraph
What F4 E3 tells you is that the reading arriving from the microwave exhaust air temperature sensor and its wiring fell outside the band the control is built to trust. The machine protects itself by refusing to heat on an unverified reading, which is why the cycle ends early.
This code, as the manufacturer publishes it
Reference| Code | Documented meaning |
|---|---|
| F4 E3 | There may be a problem with the Microwave Exhaust Air Temperature Sensor, or the associated wiring. |
What an owner observes
- Temperature drifts, or the display disagrees with the food — A probe reading a few ohms off is still inside its window, so the cabinet runs cool or hot before the code ever latches.
- The fault comes and goes with temperature — An intermittent connection opens as the metal expands and closes again when it cools, which is why the code often arrives part-way through a long cycle.
- NEAR MISS - nothing heats and no code shows at all — That is a power or element fault rather than a reading fault, and it belongs on the page for that symptom.
What produces this code, likeliest first
- A loose or corroded connector at the sensor — Ranked first because it is the failure that needs no part: the probe is fine, the joint carrying its signal is not, and heat cycling at the back of the cavity is what works a pin loose.
- A probe mounted where it now reads the wrong thing — Uncommon but real: a clip that has released lets the sensing tip sit against metal or in a draught, and the reading it returns is honest about a place nobody cares about.
What to check first, second and third
- Follow the harness for rub marks where it crosses metal — A witness mark tells you the fault is in the wire, not in the part at either end.
- Only then treat the board as a candidate — Order matters because every check above is free and the board is not.
What to try before calling
- Clear the code with a full power-down — A code that does not return was a single bad read.
About 5 min
- Let the cavity reach room temperature before anything else — A hot resistance reading means nothing, and a hot cavity is the reason half of these codes cannot be diagnosed on the spot.
About 45 min
- STOP HERE if the next step is a meter across the probe terminals — That means a panel off and a connector back-probed, which is where an owner check ends and a service call begins.
What to do before any panel comes off
Safety
Stop at the cabinet on this one. The capacitor inside a microwave power circuit holds a lethal charge after the appliance is unplugged, which is why every owner-side step above stays outside it.
When a reset is not the answer
Where an owner stops: call once the code survives a full power-down: a repeatable reading fault is a probe, a harness or a board, and telling those three apart needs a meter and the resistance table for that model line. And where nobody should wait at all: call straight away if you smell hot insulation or see discoloured wiring at the back — a connector hot enough to discolour is arcing, and that is a different and more urgent problem than the reading the code named.
Other codes on the same appliance
What this page does not cover
Applies to: the model lines that use this probe on this cavity. This page is the general reading of one code; where a more specific page exists for your family or model it is linked from the index below and it is the one to read first.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
