My 20 year old Jenn Aire electic range is going into self cleaning mode by itself.

SOURCE: Jenn-Aire locked tight!

Try turning the oven tempurature all the way to the right (past clean). That is what unlocks mine.

SOURCE: jenn aire

Maytag-Maycop-Magic Chef-Jennair-Admiral
Oven Fault Codes:
F0 Function key shorted or stuck button Clean and unstick button or replace Touch Pad or Clock
F1 Defective Touch Pad or Membrane Replace Touch Pad or Membrane
F2 Oven over heat defective Relay Board or (if present) or defective Sensor
F3 Oven Sensor Open Replace Sensor
F4 Shorted wire or Sensor locate short and correct it or replace Sensor
F5 Hardware, safety circuits disagree Replace Clock
F6 Missing AC (power) signal Check for proper voltage (plug, breaker, etc.)
F7 Function key shorted or stuck button Clean and unstick button or replace Touch Pad or Clock
F8 A/D Warning Replace Clock
F9 Door Lock Warning Check door lock circuit or Replace Clock

SOURCE: Jenn -Aire self cleaning

I turned the power off on the breaker for two minutes. When I turned it back on, the range worked again.

SOURCE: Jenn Aire lock for self clean in locked position

The LOCK INDICATOR light must be OFF. This can take up to one hour!!!

Do NOT force the door.

Leave the SELECTION and TEMPERATURE knob alone. The Temperature knob MUST be set to CLEAN

Indicator Light OFF, knobs set to CLEAN - OPEN the slide lever.

Lever open, set the knobs to OFF and away you go

SOURCE: Jenn air gas/elctric slide in range self cleaning does not work

iF THEY ALREADY REPLACED THE EXHAUST FAN , MAY WANT TO REPLACE THE HI LIMIT THERMOSTAT AT REAR OF OVEN... THE THERMOSTAT MAY RESET AFTER 20 MININUTES OF COOL DOWN..