What This Error Means

The furnace repeatedly established flame and then lost it, or repeatedly experienced a pressure-switch opening during operation, until the control reached its recycle limit.

Symptoms You May Notice

Burners ignite and then shut off; heat starts but does not continue; repeated short heating cycles; inducer restarts; eventual lockout; intermittent no-heat condition.

Common Causes

Dirty flame sensor; weak flame-sense current; poor grounding; unstable gas pressure; gas valve problem; burner carryover issue; pressure switch opening during operation; condensate restriction; vent blockage; intermittent wiring connection.

Safe Troubleshooting Steps

1. Turn off power. 2. Inspect the flame sensor and its wire connection. 3. Check furnace grounding and polarity. 4. Inspect venting and condensate components for intermittent restriction. 5. Observe whether flame is stable across all burners. 6. A qualified technician should measure flame current, inlet and manifold gas pressure, draft pressure and gas-valve voltage while the fault occurs.

Parts Commonly Involved

Flame sensor; burners; gas valve; pressure switch; inducer; condensate system; venting; integrated furnace control; wiring and ground.

When to Call a Technician

Yes, because testing generally requires live flame-current, gas-pressure or draft measurements.

Safety Notice

Do not bypass flame-sensing or pressure-switch circuits. Repeated flame loss can involve gas, venting or combustion problems.

Manufacturer Documentation