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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

Start Here

Can a single-zone mini split be used with multiple indoor units?

Can I buy a Pioneer system that only offers cooling?

Can I order different lineset lengths?

Can I use a mini-split system with fewer indoor units than the outdoor unit's zonal capacity?

Do these split-type systems function as dehumidifiers?

Do you carry hyper-heat units (-22°F)?

Do you offer any discounts?

Do you offer pre-charged linesets?

How can I obtain spare parts?

How do I determine the unit size needed for my space?

How do I find an installer for my Pioneer Mini Split purchase?

How do I make a return?

How do I use my Pioneer Rewards Points when shopping?

How does the Energy-Star Federal Tax Credit work for Pioneer systems?

How do the units receive power?

What does “multi-zone” mean?

What is the difference between Inverter+ and Inverter++ systems?

What is the life expectancy of my system?

What is the Qualified Manufacturer ID for Parker Davis HVAC International?

What types of refrigerants are used in the new models?

Where can I learn more about IRA tax credits?

Which units are rated Energy-Star?

Why do I see multiple charges on my credit card?

Why does the discount code only say "SAMPLE" when trying to refer friends?

Are Pioneer Systems Able to Be Self-Installed?

Frequently Asked Questions

Free shipping qualifications

Shipping and delivery details

What should I do if I receive an email saying my package was delivered, but I haven't received it?

Order Status & Shipping

Process for returning an item

Refund eligibility requirements

Return an item

Return fees

Return policy

Start your return

Undeliverable or refused shipments

Returns & Refunds

Shopping & Pre-Purchase

Are there recommended resources to find a professional near me?

Can the lineset be angled upward?

What gauge of wire is used for connections between the ductless mini split indoor and outdoor sections?

What hole saw size do I need for drilling walls to accommodate drain and refrigerant lines?

What is the cost and time spent on installing systems?

What torque wrench size do I need?

Where can I find wire-related information?

Who is permitted to install the A/C?

Can a wall-mounted indoor unit be set onto the ceiling instead?

Can the lineset exit from the side of the indoor unit?

Does the indoor unit require anything extra in order to be mounted to the wall?

What is the ideal height for mounting indoor units?

Installation Requirements

Installation & Setup

Can I turn Off the LED display for the indoor unit?

Do I need to restart my unit manually after the power goes out?

How can I fix my indoor air handler when the unit is not turning On?

How do I determine which breaker size and wire is needed for my system?

How does my system receive power?

What is the difference between 115V and 230V systems?

Electrical Related General Queries

Does the fan for my system shut Off in Cooling mode?

Does my system include factory pre-charged refrigerant?

How can I check the resistance of a Pioneer temperature sensor?

How can I fix leaks that are difficult to trace?

How can I locate the Pioneer model or serial number for my system?

How do I apply Pioneer Flare Leak Guard during installation?

Pioneer lineset diameter selection guide

What are the requirements for installing a mini split?

What type of oil is used for my unit?

Why did my ductless mini split system freeze on the inside air handler?

Are the linesets pre-flared when I buy a mini split?

Diagnosing and Preventing Crossed Wiring in Multi-Zone Systems

Sizing Systems & Short Cycling

What Refrigerants do Pioneer HVAC Systems Use?

HVAC Related General Queries

Why is my mini split leaking water improperly?

Routing the Drain Hose of LCAC Systems

Plumbing and Drainage Queries

Maintenance Tips

Can I operate the indoor unit without a remote control?

Remote Control Guides

Operation & Usage

CL error code

E0 error code

E1 or E2 error codes

E3, E7, or E8 error codes

E4 error code

E6 error code

E9 error code (Diamante Series)

E9 error code (Quantum Series)

EF error code

EU error code

F4 error code

F5 error code

F6 error code (Diamante Series)

F6 error code (Quantum Series)

F7 error code

F8 error code

Fd error code

Fy error code

H1 or H2 error code (Multi-Zone Quantum Ultra Series)

P0 error code

P1 error code

P2 error code

P4 error code (Diamante Series)

P5 error code

P6 error code

P7 error code

P8 error code

P9 error code

PA error code (Multi-Zone Quantum Ultra Series)

E9/P0 error codes

Indoor unit displaying 0A code

Troubleshooting (WYT-19 & WYT-22)

E1/EL 01/EL01 error codes

E3/EH 03/F5/EC 07 error codes

EC/EL 0C error codes

F4/EC51 error codes

LCAC error codes

P0/PC00 error codes

P1/PC01 error codes

P2/PC02 error codes

PC 03/PC03 error codes

P4/PC 04/PC04 error codes

Troubleshooting (WYS, CYB, RYB, UYB, & FYB)

Troubleshooting (Discontinued Products)

IDU Disassembly for Diamante Essenza / Diamante Pro / Quantum Ultra - High Wall Mount

ODU Disassembly for Diamante Essenza / Diamante Pro / Quantum Ultra - High Wall Mount / Quantum Hyperformance

Disassembly Guides

What is the indoor unit’s weight and dimensions?

Dimensions & Clearances

PT Chart (YN009GLSI24RPG)

PT Chart (YN012GLSI24RPG)

PT Chart (YN018GLSI24RPG)

PT Chart (YN024GLSI24RPG)

PT Charts - CYT-24

PT Charts - RYT-24

PT Charts - UYT-24

PT Chart (YN012ALUI17RPD)

PT Chart (YN012GLUI17RPD)

PT Chart (YN018GLUI17RPD)

PT Chart (YN024GLUI17RPD)

PT Chart (YN036GLUI17RPD)

PT Charts - WYT-17

PT Chart (YN009ALSI20RPF)

PT Chart (YN009GLSI20RPF)

PT Chart (YN012ALSI20RPF)

PT Chart (YN012GLSI20RPF)

PT Chart (YN018GLSI20RPF)

PT Chart (YN024GLSI20RPF)

PT Chart (YN030GLSI20RPF & YN036GLSI20RPF)

PT Charts - WYT-20

PT Chart (YN009ALSI24RPG)

PT Chart (YN012ALSI24RPG)

PT Charts - WYT-24

PT Chart (YN009GLSI25RPH)

PT Chart (YN012GLSI25RPH)

PT Chart (YN018GLSI25RPH)

PT Chart (YN024GLSI25RPH)

PT Charts - WYT-25

PT Chart (YN012GLUI25RPQ)

PT Charts - WYT-FA

PT Chart (YN020GLSI24M2G)

PT Chart (YN030GLSI24M3G)

PT Chart (YN040GLSI24M4G)

PT Chart (YN050GLSI24M5G)

PT Charts - YNL-24

PT (Pressure Temperature) Charts

Product Data & Technical Information

How can I access manuals and technical documents?

What is the telephone number to receive Tech Support?

Contact Support

Warranty coverage

Warranty durations

Warranty Terms

Warranty & Support

Understand the difference between Diamante Pro and Diamante Ultra systems

Wall Mounted WYT-19 Diamante Pro Series

Wall Mounted WYT-22 Diamante Ultra Series

Technical Documentation (Diamante Series)

Connect your WYT-19 Diamante Series with the Pioneer Airlink App

Connect your WYT-22/WYT-24/WYT-25 Series with the Pioneer Airlink App

Integrate the Pioneer Airlink App with Apple's Smart Home Environment

Pioneer Airlink App

Diamante Series Systems (WYT-19, WYT-22)

Understand how Cased A-Coils interact with furnaces and other heating units

Technical Documentation (DYR Series)

Ducted Central Split DYR Series

Connect CYB, RYB, and UYB systems with the NetHome Plus App

Connect WYS-20 and WYS-22 systems with the NetHome Plus App

NetHome Plus

Quantum Series Systems (WYS/CYB/RYB/UYB/FYB)

Discontinued Products

P4 error code (Quantum Series)Updated 2 hours ago

Introduction

Troubleshooting Diagram