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Lennox SLP99DFV gas furnaces error codes

17 furnace error codes for Lennox SLP99DFV gas furnaces, what each one means and what to try, paraphrased from Lennox's own source. Codes vary by model, so confirm in your own manual.

All codes

E110

What it means: Line voltage low (lower than the nameplate rating). This one often needs a licensed technician.

What to try

  1. Check voltage.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E113

What it means: Line voltage high (higher than the nameplate rating). This one often needs a licensed technician.

What to try

  1. Check voltage.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E115

What it means: Low 24V control voltage; the control restarts when it recovers. This one often needs a licensed technician.

What to try

  1. Have a technician check the 24V control voltage.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E124

What it means: Active communicating thermostat signal missing for more than 3 minutes. You can usually fix this yourself.

What to try

  1. Check connections and cycle power on the thermostat.

E200

What it means: Hard lockout: the rollout circuit is or was open. This one often needs a licensed technician.

What to try

  1. Have a technician check the rollout switch.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E204

What it means: Gas valve is mis-wired. This one often needs a licensed technician.

What to try

  1. Have a technician check the gas valve.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E207

What it means: Hot surface igniter reads open. This one often needs a licensed technician.

What to try

  1. A technician measures the igniter and replaces it if open.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E223

What it means: Low pressure switch failed open. This one often needs a licensed technician.

What to try

  1. A technician checks vent, inducer and switch pressure.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E225

What it means: High pressure switch failed open. This one often needs a licensed technician.

What to try

  1. A technician checks vent, inducer and switch pressure.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E240

What it means: Low flame current while running. This one often needs a licensed technician.

What to try

  1. A technician cleans or replaces the flame sensor and checks grounding.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E241

What it means: Flame sensed out of sequence; flame still present. This one often needs a licensed technician.

What to try

  1. Shut off the gas and have a qualified technician check the gas valve for a leak.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E250

What it means: Limit switch circuit is open. This one often needs a licensed technician.

What to try

  1. Check why the limit is tripping (overfired or low air flow); have a technician check it.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E270

What it means: Soft lockout: too many retries with no flame sensed. This one often needs a licensed technician.

What to try

  1. A technician checks gas flow, igniter and flame sensor.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E291

What it means: Restricted airflow: too little air for minimum firing rate. You can usually fix this yourself.

What to try

  1. Have a technician check the air flow and filter.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E292

What it means: Indoor blower motor will not start. This one often needs a licensed technician.

What to try

  1. A technician replaces the motor or wheel if needed.

Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: Installation Instructions SLP99DFV, Integrated Control Diagnostic Codes (Lennox).

E311

What it means: Heat rate reduced: the furnace blower is in cutback mode due to restricted airflow. You can usually fix this yourself.

What to try

  1. Replace the filter or fix duct restrictions.

E312

What it means: Restricted airflow in cooling or fan mode. You can usually fix this yourself.

What to try

  1. Replace the filter if needed and check the ductwork.

Source

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