Keeprite E4 Error Code

What does Keeprite E4 mean?

The IGC (Integrated Gas Control) board is displaying 4 LED flashes, indicating an open limit circuit. Either the primary high-limit switch or the flame rollout switch has opened, cutting gas heat to prevent overheating. The unit will attempt to resume heating once the switch resets, but repeated trips escalate to a lockout condition.

Symptoms

• Gas burners shut off mid-cycle while the blower continues to run
• No heat output despite the thermostat calling for heat
• IGC board LED flashes exactly 4 times in a repeating pattern
• Unit short-cycles: heat starts briefly then cuts out

Common causes

• Dirty or clogged air filter restricting airflow across the heat exchanger
• Loose or slipping blower wheel reducing supply airflow
• Restricted or undersized supply/return ductwork causing heat buildup
• Flame rollout switch tripped due to cracked heat exchanger or improper combustion
• Blocked flue or vent pipe preventing exhaust from clearing the heat exchanger

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Diagnostic steps

1. Inspect and replace the air filter

   Locate the filter and check its condition. A clogged filter is the most common cause of limit trips; replace it if it is visibly dirty or has been in service more than 90 days.

2. Check the blower wheel and motor

   With power off, inspect the blower wheel for debris and verify it is tight on the motor shaft. A loose wheel reduces airflow and causes the heat exchanger to overheat.

3. Inspect the vent and flue for blockages

   Examine the flue pipe from the unit to the termination point for obstructions such as bird nests, ice, or collapsed sections. Clear any blockages found.

4. Manually reset the limit switch

   Cycle power at the unit disconnect to allow the limit switch to reset. If the 4-flash code immediately returns, the root cause has not been resolved.

5. Inspect the flame rollout switch

   Locate the rollout switch on the burner assembly. If it has tripped, investigate for combustion gas spillage before resetting it. A rollout trip without an obvious blockage suggests a cracked heat exchanger.

When to call a professional

If the 4-flash limit fault returns after replacing the filter and clearing vent obstructions, or if the rollout switch has tripped, engage a licensed HVAC technician immediately. A rollout condition can indicate a cracked heat exchanger that allows combustion gases to enter occupied space — this is a life-safety issue requiring professional inspection and combustion analysis before the unit is returned to service.