Electric oven will not heat, display shows F1 shortly after a cooking program is selected.

Safety first: Switch off the range at the wall isolator and remove the fuse or turn off the circuit breaker. Allow the oven to cool completely before working inside.

Steps to check:

• Power reset: Turn off power for 5 minutes, then restore. If F1 returns immediately when you start the oven, continue below.
• Locate the sensor: Inside the main oven cavity, find the slim metal probe (temperature sensor) usually at the rear upper corner, secured with 2 screws.
• Inspect wiring: Remove the rear panel of the cooker. Trace the sensor wires to the main control PCB. Check for burnt, loose, or broken connectors. Reseat any loose plugs.
• Test resistance: With a multimeter set to ohms, disconnect the sensor plug and measure across the sensor terminals. A typical Rangemaster oven sensor is around 1000–1100 Ω at room temperature. If it reads open (OL) or near 0 Ω, the sensor is faulty and must be replaced.
• Replace sensor if faulty: Remove the 2 screws inside the oven, gently pull the sensor into the cavity, transfer the wiring, and refit. Ensure the gasket or seal is correctly seated to prevent heat loss.
• If sensor tests OK: The fault may be on the main oven control PCB. Visually inspect for burnt tracks or components. PCB replacement is more complex and is best handled by a qualified Rangemaster technician.

Do not operate the oven with a bypassed or shorted sensor; this is a fire and burn hazard.