Carrier 58MVP Error Code 23: Pressure Switch Did Not Open
What Does Code 23 Mean?
Status code 23 on the Carrier 58MVP indicates a pressure switch did not open when the control expected it to. During normal operation the pressure switches must both close (when the inducer creates draft) and open (when it stops); a switch that stays closed when it should be open fails this self-check. Carrier's guide lists obstructed pressure tubing and a pressure switch stuck closed.
On this variable-capacity furnace there are separate low-heat and high-heat pressure switches that prove adequate venting for each stage. A switch stuck in the closed position — or tubing plugged so the switch cannot sense the change in draft — defeats that safety verification. Because the fault is about a switch not opening (rather than failing to prove draft), Carrier treats it as lower severity, but it still needs correction so the safety interlocks work reliably.
What You'll Notice
- The furnace may run but the board logs code 23
- Heating can be intermittent or the furnace hesitates between cycles
- The pressure tubing may look aged, cracked, or pinched
- The board LED flashes code 23
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Obstructed pressure tubing | Most common | ✗ Call a pro → |
How This Is Diagnosed
A technician inspects the pressure tubing for obstruction, kinks, or moisture, and tests the pressure switch to confirm it opens and closes at the correct pressures. A switch stuck closed is replaced; blocked tubing is cleared or replaced. This involves the combustion and venting safety circuit and is a professional task.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The board repeatedly logs code 23
- The furnace heats erratically or hesitates between cycles
- The pressure tubing looks cracked, pinched, or has moisture inside
Frequently Asked Questions
What does code 23 mean on a Carrier 58MVP?
A pressure switch did not open when the control expected it to, usually from obstructed pressure tubing or a switch stuck closed. A technician should inspect the switch and tubing.
Is code 23 an emergency?
It is a lower-severity fault than the draft-proving codes, but the pressure-switch safety circuit should still be repaired so the furnace's interlocks work correctly.
Sources
✓ Verified against manufacturer service manual — March 2026