Furnace attempts to start but shuts down with E04; blower may run briefly.

Safety: Turn off power before removing panels. Components may be hot; allow time to cool.

• Replace or clean filter: Locate the furnace filter in the return air cabinet or filter rack. Remove and inspect. If dirty, replace with the correct size and MERV rating recommended by Wolf. Never operate without a filter.
• Check airflow: Walk through the home and ensure all supply registers and return grilles are open and not blocked by furniture, rugs, or drapes.
• Inspect blower motor: Remove the blower compartment door. Check for dust buildup on the blower wheel and motor. Clean with a vacuum and soft brush. Spin the blower wheel by hand; it should rotate freely. If the motor is hot to the touch, noisy, or fails to start, it may be failing.
• High limit switch: Locate the high limit switch on the heat exchanger panel (often a disc or rectangular device with two wires). Ensure wiring is secure. Do not bypass the switch. If E04 persists after airflow issues are corrected, the Wolf high limit switch may be weak and should be tested and replaced by a technician.