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<h2 id="introduction"><u>Introduction</u></h2><p>The &quot;F4&quot; error code indicates a T4 outdoor ambient temperature sensor failure. This article is for <a href="https://www.pioneerminisplit.com/collections/vertex-ducted-central-split" target="_blank" rel="noopener noreferrer">Vertex Ducted Central Split (DYC-18) systems</a>.&#xA0;</p><p>The error code shows on the display board.&#xA0;</p><p><strong id="isPasted">Cause:</strong> Sensor reading error.&#xA0;</p><h2 id="troubleshooting-diagram"><u>Troubleshooting Diagram</u></h2><p><img src="https://attachments.gorgias.help/Q9r0k7BYaV2vg13y/hc/9JWjXVxG8m6DvMqm/2026012918-4f9a9455-db4e-4abe-b560-7d4fc4f45b55-dyc18_troubleshooting_f4.png" style="width: 800px;" class="fr-fic fr-dib fr-bordered"></p><p><br></p>

The "F4" error code indicates a T4 outdoor ambient temperature sensor failure. This article is for Vertex Ducted Central Split (DYC-18) systems. The error code shows on the display board. Cause: Sensor reading error.

F4 Error Code

Troubleshooting

By Error Code

Error Codes for Vertex Ducted Central Split (DYC-18) Systems

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CL error code

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F4 Error CodeUpdated 4 days ago

Introduction

Troubleshooting Diagram