Error Code Status Code 45

Carrier 58MVC Error Code Status Code 45: Control Circuitry Lockout

TL;DR
Auto-reset after 1 hour due to: 1) Flame sense circuitry failure, 2) Software check error, 3) Gas valve relay stuck open. Reset power to clear lockout. If status code re-occurs when power is re-applied replace variable speed furnace control.
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 45 Mean?

Auto-reset after 1 hour due to: 1) Flame sense circuitry failure, 2) Software check error, 3) Gas valve relay stuck open. Reset power to clear lockout. If status code re-occurs when power is re-applied replace variable speed furnace control.

Common Causes

Cause Likelihood DIY?
Flame sense circuitry failure on control board ✗ Call a pro →
Software check error ✗ Call a pro →
Gas valve relay stuck open ✗ 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