Boiler displays E2 and shuts down shortly after starting

Safety first: Turn off electrical power and close the gas shutoff valve before opening the boiler cabinet.

• Step 1 – Observe behavior: Reset the boiler and watch through the sight glass. If the burner lights and then goes out within a few seconds, the control is losing flame signal.
• Step 2 – Clean flame sensor: Remove the flame sensor and clean the sensing rod with fine abrasive pad until bright. Reinstall ensuring it is fully in the flame path.
• Step 3 – Check vent and air intake: Inspect the Rheem boiler’s concentric vent or separate intake/exhaust pipes for obstructions (ice, leaves, bird nests, debris). Clear any blockage and ensure proper termination clearances.
• Step 4 – Verify gas supply stability: If possible, have a technician measure inlet and manifold gas pressure while the boiler is firing. Fluctuating or low pressure can cause flame dropout and must be corrected by the gas supplier or installer.
• Step 5 – Burner inspection: Remove and inspect the burner assembly for rust, debris, or blocked ports. Clean per Rheem’s instructions. If burner damage is present, replace the burner.
• Step 6 – Advanced diagnostics: If cleaning and gas supply checks do not resolve E2, the gas valve or main control PCB may be failing to maintain stable flame. These parts should be tested and replaced by a qualified Rheem technician.

Warning: Do not operate the boiler with known venting or gas supply issues. This can lead to carbon monoxide hazards.