Lennox SLP98UHV Error Code E 272: Soft Lockout - Pressure Switch Recycle
What Does Code E 272 Mean?
Error code E272 on the Lennox SLP98UHV indicates a soft lockout that occurred after the system exceeded the maximum number of recycle attempts, with the last recycle being caused by the pressure switch opening during operation. The furnace tried multiple times to maintain a heating cycle, but the pressure switch kept interrupting by opening.
This code points to a persistent venting or draft problem. Unlike a single pressure switch trip (which might be caused by a momentary gust of wind), E272 means the issue happened repeatedly, reaching the control board's retry limit. The furnace has locked itself out to prevent further unsuccessful attempts.
The underlying cause is the same as codes E223 and E225 — the draft pressure is not being maintained at the level required by the pressure switch. A technician should thoroughly inspect the entire vent run for partial blockages, check the inducer motor for proper operation and amp draw, verify the pressure switch hose connections, and measure the actual draft pressure against the switch settings.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Persistent venting problem causing repeated pressure switch trips | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace has locked out and will not restart
- The code keeps returning after the lockout period clears
- You suspect ice or debris may be blocking the exhaust vent outside
✓ Verified against manufacturer service manual — March 2026