Error Code Status Code 43

Carrier 58MVC Error Code Status Code 43: Low-Heat Pressure Switch Open While Medium-Heat Pressure Switch Is Closed

TL;DR
This status code can occur as a result of the low heat pressure switch LPS not making during a call for heat. Keep in mind that whenever status code 43 occurs the variable speed furnace control shuts unit down, turns the inducer off, and gas remains off. Applies to LOW, MEDIUM, OR HIGH HEAT. If the medium heat pressure switch MPS makes and the low heat pressure switch LPS is still open the variable speed furnace control starts flashing status code 43, shuts unit down, and waits 2 minutes before restarting the heating cycle.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code Status Code 43 Mean?

This status code can occur as a result of the low heat pressure switch LPS not making during a call for heat. Keep in mind that whenever status code 43 occurs the variable speed furnace control shuts unit down, turns the inducer off, and gas remains off. Applies to LOW, MEDIUM, OR HIGH HEAT. If the medium heat pressure switch MPS makes and the low heat pressure switch LPS is still open the variable speed furnace control starts flashing status code 43, shuts unit down, and waits 2 minutes before restarting the heating cycle.

Common Causes

Cause Likelihood DIY?
Low heat pressure switch LPS not making contact ✗ Call a pro →
Open circuit between low heat pressure switch LPS and furnace control ✗ Call a pro →
ORANGE wire interconnecting low heat pressure switch LPS and control ✗ Call a pro →
Low gas pressure switch LGPS continuity issue (if used) ✗ Call a pro →

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Carrier 58MVC Series 100 Troubleshooting Guide, p.9 & p.34