In brief
Jenn-Air documents F4 E3 as a possible problem with the microwave exhaust air temperature sensor or its wiring. That sensor watches the temperature of the air leaving the microwave section, so the section cannot confirm it is cooling properly while the code shows. Do not use the microwave section until it is resolved.
Error codes
Reference| Code | Meaning |
|---|---|
| F4 E3 | There may be a problem with the Microwave Exhaust Air Temperature Sensor, or the associated wiring. |
What you observe
- Little or no air from the exhaust vent — Weak exhaust airflow points at a blockage or a slow fan.
- The code appears after long use — Exhaust air warms over a long run.
- The vent area feels hotter than usual — Hot exhaust air suggests a cooling problem the sensor may be reporting accurately.
- NEAR MISS: a magnetron or wave guide temperature code — Those name different sensors inside the microwave section, with their own checks.
What triggers the code, in likelihood order
- The exhaust air temperature sensor — Ranked first because the documented meaning for F4 E3 names the sensor or its wiring rather than a temperature limit, and the sensor is the part sitting in the warm exhaust stream.
- Its connector or wiring — Connections inside the cabinet loosen with heat and vibration.
- Exhaust air that really is too hot — A blocked exhaust path, from trim, cabinetry or grease, makes the air run hot, and a healthy sensor reports it.
What to check first, and why
- Check the exhaust vents — Look for trim, cabinetry, stored items or grease restricting the vents on the unit.
- Feel for airflow — While a short heat runs with a cup of water inside, hold a hand near the exhaust vent to feel for air.
- Reset once, cold — Let the unit cool, then reset at the breaker.
What an owner can safely do
- Clear and clean the vents — Remove anything blocking the vents and wipe grease from the vent grilles with the power off.
Tools: soft cloth, mild degreaserAbout 10 min
- Let the unit cool — Leave the microwave section off for half an hour.
About 30 min
- Reset at the breaker — Breaker off for a few minutes, then on.
About 5 min
- Stop before any panel comes off — Everything past this point needs live measurements or a panel removed; that is the line between an owner check and a service call.
Safety first
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Exhaust vents can be hot after use, and the parts behind them are high-voltage; clean only the outer grilles, with the power off and the unit cool. Hot trim, a burning smell or discolored plastic around the control are reasons to leave the oven off at the breaker, not to keep testing.
When it is a service call
Call for service if F4 E3 returns after the vents are clear and the unit has cooled and been reset, or if no air comes from the exhaust vent while it runs. The sensor and cooling fan are inside the microwave cabinet with high-voltage parts.
Nearby codes on the same oven line
Scope of this code reading
What this covers: F4 E3 as Jenn-Air documents it for Jenn-Air combination units with a microwave section whose code list carries F4 E3. What it does not cover: ovens without a microwave section, other microwave sensor codes, and models that read F4 E3 differently, or the wiring colors, part numbers and test values of any one model. A model-specific page for your unit, where one exists, outranks this general reading.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
