Boiler shows E11 and locks out; often associated with gas valve or ignition control issues.

Safety first: Turn off power and gas. Gas valve work must comply with local codes; if you are not qualified, contact a licensed technician.

• Step 1 – Check wiring: Inspect the gas valve connector and wiring harness. Ensure all terminals are tight and free of corrosion. Reseat plug-in connectors.
• Step 2 – Verify gas shutoff position: Confirm the manual gas shutoff at the valve is fully open and that any service cocks are in the correct position.
• Step 3 – Listen during ignition: Restore power and call for heat. Listen for the click of the gas valve opening during the ignition sequence. If there is no click and E11 appears, the valve may not be energizing.
• Step 4 – Coil and voltage tests (pro only): A technician should measure voltage at the gas valve during ignition and check coil resistance. If voltage is present but the valve does not open, the valve is defective.
• Step 5 – Replace gas valve: If confirmed faulty, replace the gas valve with the exact Bradford White-specified part and perform leak testing and combustion checks.

Warning: Never attempt to disassemble or repair a gas valve; always replace as a complete assembly.