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<h2 id="isPasted"><u>Introduction</u></h2><p>The &quot;P4&quot; error code indicates the outdoor unit is undergoing discharge temperature overheating protection. This article is for Quantum series systems.</p><h2 id="troubleshooting-diagram"><u>Troubleshooting Diagram</u><u><img src="https://attachments.gorgias.help/Q9r0k7BYaV2vg13y/hc/9JWjXVxG8m6DvMqm/2025111414-088ced10-b2cf-421a-a0d5-071481b14978-p4_troubleshooting_diagram.png" style="width: 1000px;" class="fr-fic fr-dib fr-bordered"></u><br></h2>

This error code indicates the outdoor unit is undergoing discharge temperature overheating protection. This troubleshooting article is for Quantum series systems.

P4 Error Code (Quantum Series)

Troubleshooting

By Error Code

Pioneer Offers Hyper-Heat Units

Pioneer Systems Offer Both Heating and Cooling Functions

Understand the Difference Between 115V and 230V Systems

Understand the Refrigerants Used for Each Model

How to Choose a System

Mini Splits are Capable of Using Fewer Indoor Units than the Outdoor Unit’s Zonal Capacity

Pioneer Mini Splits Function as Dehumidifiers

Pioneer Offers Different Lineset Lengths

Pioneer Offers Pre-Charged Linesets

Pioneer Offers Pre-Flared Linesets

Pioneer Systems Include Factory Pre-Charged Refrigerant

Single-Zone Mini Splits Cannot be Used with Multiple Indoor Units

Understand the Life Expectancy of Pioneer Systems

Mini-Split Basics

Determine the Unit Size Needed for Your Space

Match the Lineset Diameter to Your Pioneer Indoor Unit

Understand Why Short Cycling Occurs When Sizing Systems

Sizing & Efficiency Guide

Start Here

Understand the Differences Between Inverter+ and Inverter++ Systems

Understand the Differences Between the Wall-Mounted Ductless Mini Splits

Understand Which Units are Rated Energy-Star

Compare Models

Learn About the Discounts Available

Learn About the Energy-Star Tax Credits Available for Pioneer Systems

Learn More about IRA Tax Credits

Learn Why Your Pioneer Discount Code Only Says "SAMPLE"

Redeem Your Pioneer Rewards Points When Shopping Online

Understand How to Manage Multiple Credit Card Charges with Pioneer

Financing & Payment

Learn About Our Shipping and Delivery Details

Understand the Qualifications for Free Shipping

Order Status & Shipping

Diamante Essenza (WYT-17) Overview

Diamante Pro (WYT-20) Overview

Quantum Ultra High-Wall (WYT-24) Overview

Quantum Hyperformance (WYT-25) Overview

Quantum Fresh (WYT-FA) Overview

Quantum Ultra Ceiling Cassette (CYT-24) Overview

Quantum Ultra Ducted Ceiling Concealed (RYT-24) Overview

Quantum Ultra Floor-Ceiling Flex (UYT-24) Overview

Vertex Ducted Central Split (DYC-18) Overview

Quantum Ultra - Multi-Zone Overview

Product Line Overviews

Find Out How to Complete Returns

Figure Out How to Start Your Return

Learn About Our Return Policy

Learn About Our Policy for Undeliverable or Refused Shipments

Understand How to Return an Item

Understand the Eligibility Requirements for Refunds

Understand Our Return Fees

Understand Our Return Process

Returns & Refunds

Shopping & Pre-Purchase

Open Ceiling and Install Hanging Hook for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Select the Indoor Unit Installation Location for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Set Up the Indoor Unit Condensate Piping Connections for Quantum Ultra Ceiling Cassette (CYT-24) systems

Suspend the Air Handler Unit for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Understand the Additional Leakage Sensor for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Understand the Air Duct Parameters for Auxiliary Duct Usage

Cassette Units

Select the Indoor Unit Installation Location for Quantum Ultra Ducted Ceiling Concealed Systems

Select the Indoor Unit Installation Location for Vertex Ducted Central Split Systems

Understand the Additional Leakage Sensor for Quantum Ultra Ducted Ceiling Concealed (RYT-24) Systems

Ducted Units

Find an Installer for Your System

Find Professionals to Install Your Pioneer System

Learn Who is Permitted to Install Your System

Understand if Our Systems can be Self-Installed

Understand the Cost and Time Spent on Installing Systems

First-Time Setup

Angle Linesets Upward

Complete the Safety Checks and Test Run

Connect the Drain Hose for LCAC Systems

Find Out if a Wall-Mounted Indoor Unit can be Set onto Ceilings

Find Out if the Indoor Unit Requires Anything Extra in Order to be Wall-Mounted

Find Out the Ideal Height for Mounting Indoor Units

Learn the Gauge of Wire Used for Ductless System Connections

Setup the Lineset to Exit from the Side of the Indoor Unit

Understand 6-Foot Plastic Whips and 4-Lead Mini Split Connection Wire

Understand the Drilling Details to Accommodate Drain and Refrigerant Lines

Understand the Requirements for Installing Your System

Understand the Torque Wrench Size for Installing Your System

Installation Requirements

Understand the Meaning of “Multi-Zone”

Multi-Zone Units

Air Evacuation and Bleeding the Circuit for Wall-Mounted Systems

Connect the Drain Hose for Wall-Mounted Systems

Connect the Fresh Air Pipe for Quantum Fresh Systems

Connect the Power/Signal Electrical Wiring for Wall-Mounted Systems

Connect the Refrigerant Piping to the Indoor Unit for Wall-Mounted Systems

Connect the Refrigerant Piping to the Outdoor Unit for Wall-Mounted Systems

Drill the Piping Wall Hole for Wall-Mounted Systems

Install the Indoor Unit Mounting Plate for Wall-Mounted Units

Mount the Indoor Unit for Wall-Mounted Systems

Mount the Outdoor Unit for Wall-Mounted Systems

Prepare the Refrigerant Piping of the Indoor Unit for Wall-Mounted Systems

Select the Indoor Unit Installation Location for Quantum Fresh Systems

Select the Indoor Unit Installation Location for Quantum Ultra Floor-Ceiling Flex Systems

Select the Indoor Unit Installation Location for Wall-Mounted Systems

Select the Outdoor Unit Installation Location for Wall-Mounted Systems

Set Up the Outdoor Unit Condensate Water Drainage for Wall-Mounted Systems

Understand the Additional Leakage Sensor for Wall-Mounted Systems

Understand the Additional Leakage Sensor for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Single-Zone Units

Installation & Setup

Front Panel Displays for Quantum Ultra Ceiling Cassette Systems

Front Panel Display for Quantum Ultra Floor-Ceiling Flex Systems

Front Panel Displays for Wall-Mounted Systems

Wired Display Board Layout for Quantum Ultra Ducted Ceiling Concealed Systems

Display Layouts

CL error code

Clean the Anti-Dust Filters for Diamante Essenza and Pro Systems

Clean the Anti-Dust Filters for Quantum Ultra High Wall-Mount and Hyperformance Systems

Clean the Anti-Dust Filters for Quantum Fresh Systems

Cleaning the Anti-Dust Filters for Quantum Ultra Ceiling Cassette Systems

Clean the Anti-Dust Filters for Quantum Ultra Ducted Ceiling Concealed Systems

Clean the Anti-Dust Filters for Quantum Ultra Floor-Ceiling Flex Systems

Filter Cleaning & CL Code

Determine the Breaker Size and Wire Needed for Your System

Diagnose and Prevent Crossed Wiring in Multi-Zone Systems

Understand How the System Receives Power

Understand if Restarting Your Unit Manually is Required After the Power Goes Out

Electrical Related Queries

Locate the Model or Serial Number for Your System

Turn Off the LED Display for the Indoor Unit

General Queries

Check the Resistance of a Pioneer Temperature Sensor

Find Out the Type of Oil Used for Our Units

Fix Your Indoor Air Handler When the Unit is Not Turning On

Understand How Cased A-Coils Interact with Furnaces and Other Heating Units

Understand if the System's Fan Shuts Off in Cooling Mode

HVAC Related Queries

Maintenance Tips

Activate Auto Mode

Activate the Child-Lock Function

Activate Cooling Mode

Activate Dry Mode

Activate Energy Saver (ECO) Mode

Activate Fan-Only Mode

Activate the Fresh Air Feature

Activate Gentle Wind Mode

Activate Heating Mode

Activate the I Feel feature

Activate the Memory Feature

Activate Mute Mode

Activate the Self-Clean Feature

Activate Sleep Mode

Activate the Timer On/Timer Off Function

Activate Turbo Mode

Activate 46°F Freeze Protection

Understand the Auto-Restart Feature

Understand the Voice Control Feature

Modes Explained

Turn the LED Display On or Off

Control the Airflow for Ceiling Cassette Systems

Control the Airflow for Ducted Ceiling Concealed Systems

Control the Airflow for Floor-Ceiling Flex Systems

Control the Airflow for High Wall-Mounted Systems

Control System Airflow

Operating Instructions

Activate Heat Mode Using Diamante Pro Series Remotes

Replace Batteries for Remote Controls

Use the Emergency Manual Button to Operate the Indoor Unit Without a Remote Control

P4 Error Code (Quantum Series)Updated a day ago

Introduction

Troubleshooting Diagram