Boiler locks out with E03; fan may run briefly then stop, no ignition

Safety: Switch off power to the Crown boiler. Do not operate the boiler with a suspected flue blockage.

• Inspect venting: Check the entire length of the exhaust and intake pipes for obstructions, sagging, or water accumulation. Outside terminations must be clear of snow, ice, and debris.
• Check condensate drain: On Crown condensing models, verify the condensate trap and drain line are not clogged or frozen, which can cause water to back up into the flue path.
• Inspect air pressure switch tubing: Open the front panel and locate the air pressure switch on the combustion air fan housing. Inspect the silicone tubes for cracks, kinks, or disconnections. Reattach or replace as needed.
• Test fan operation (visual): With the cover back on and power restored, start a call for heat and listen for the combustion fan. If the fan does not start or is very noisy, it may be failing and should be replaced by a technician.
• Do not bypass safety: Never jumper or bypass the air pressure switch. If E03 persists after clearing venting and tubing, contact a qualified Crown boiler service technician.