Fault Code E08 – Lennox Series Pro 8

Meaning: A motor, fan, valve, or actuator did not respond as expected.

Common causes

• Loose or damaged wiring/connector
• Connector corrosion, moisture intrusion, or contamination
• Out-of-range operating conditions
• Component wear or intermittent failure
• Improper installation or setup
• Communication wiring mismatch
• Voltage drop during compressor start
• Short circuit or internal module failure
• Safety interlock activation

What to check first

1. Power down the unit before inspection and allow it to cool (if hot)
2. Turn power off at the disconnect before inspecting indoor/outdoor communication wiring
3. Verify connectors are seated and wiring is intact (no pinches/cuts/burn marks)
4. Confirm supply power is within specification for your unit
5. Remove debris and ensure proper ventilation/airflow
6. After correcting the suspected cause, power-cycle and retest
7. Check for terminal corrosion and tighten connections to manufacturer torque guidance

Is it safe to keep running?

No. Stop operation and troubleshoot before continuing.

Reset guidance

After correcting the underlying issue, clear the fault by power-cycling the unit, then retest during normal operation. If the code returns, stop and escalate to service diagnostics.

When to call service

• The code returns immediately after basic checks
• There are visible signs of damage, overheating, or burning odor
• The unit will not start or shuts down repeatedly
• You are not comfortable performing electrical diagnostics safely

General reference only. Not affiliated with manufacturers. Meanings describe common patterns and may vary by exact model/version—always confirm with your model’s service manual.