Ingersoll Rand Furnace Error Code E3.3

E3.3 means the second-stage pressure switch (PS2) is detected as closed when it should be in the open position. This is a safety fault that prevents the furnace from operating. The control board monitors PS2 for correct open and closed states during the ignition sequence, and a closed switch at the wrong time triggers this lockout.

Start by cycling power off and back on, then visually inspect PS2 for correct orientation and check its wiring harness for shorts or damage. Use a multimeter to measure 24 volts AC across PS2 terminals (brown wire to yellow wire) to confirm proper voltage. If the switch remains closed at rest with no inducer running, the switch should be replaced. If wiring damage is found, repair or replace the affected section of the harness.

If the repair requires only wiring corrections or switch reorientation, costs may be limited to a service call fee, typically in the range of $75 to $150. If a new second-stage pressure switch is needed, parts generally range from $20 to $80 depending on the specific switch, with labor bringing the total repair to $100 to $250 in most cases. Control board replacement, if required, would increase costs significantly.

Cycling the power off and then back on is the recommended first step and may temporarily clear the code if the fault was a transient glitch. However, if PS2 is physically stuck closed, shorted by wiring, or incorrectly installed, the error will return as soon as the furnace attempts to run again. A power cycle should be followed by a full inspection of PS2 and its wiring.

Yes, the furnace locks out with E3.3 precisely because the pressure switch is part of the combustion safety system. A pressure switch stuck closed could indicate a fault that, if bypassed, might allow the furnace to operate outside of safe pressure parameters. The furnace should not be operated with a known faulty pressure switch, and the condition should be diagnosed and corrected before restoring normal operation.