Work Performed: Inspected Lennox furnace (installed in 2009) showing a pressure switch error code. Tested pressure switch, venting, and condensate system. Measured pressures using a manometer, confirming pressures are exceeding rated limits. Verified with volt meter that the pressure switches intermittently failing to close or open, triggering the error code. Tested other furnace functions, including combustion analysis and general inspection. Results: Furnace is still operational at this time. Pressure switches require replacement to ensure continued safe and reliable operation. Recommendation: Recommend replacing the pressure switches to address the intermittent failure.