Mechanic Wiki: How to Perform Coolant Bleed on Kia EV4 with LAUNCH X431

Learn how to bleed coolant on a Kia EV4 using a LAUNCH X431 scanner. Step-by-step guide, troubleshooting, and safety tips for EV cooling system maintenance.

Published: June 28, 2026

Quick Answer

To perform a coolant bleed on a Kia EV4 using a LAUNCH X431 scanner, ensure the vehicle is on level ground with the ignition on. Connect the scanner, navigate to Diagnosis > Electric/Hybrid > Coolant Bleeding, activate the electric water pump via on-screen prompts, then manually open the bleeder valve (if equipped) until a steady stream of coolant flows with no bubbles. Top off the reservoir and run another cycle until the scanner confirms “Bleed Complete.” The process typically takes 10–20 minutes.

Why Coolant Bleeding Is Critical for the Kia EV4

Trapped air in the cooling system of an electric vehicle like the Kia EV4 is more than just an annoyance—it can lead to serious performance and safety issues. The EV4 uses a sophisticated thermal management system to keep the high-voltage battery, electric motor, and cabin heater operating within optimal temperature ranges. When air pockets form, they disrupt coolant flow, causing:

Battery overheating: Without proper circulation, the battery pack can exceed safe temperatures, reducing efficiency and potentially triggering a shutdown.
Inefficient heater performance: The electric heater relies on hot coolant to warm the cabin. Air pockets block flow, leaving you with cold air on a winter morning.
Faulty temperature readings: Air bubbles can confuse sensors, leading to erratic gauge behavior or false warnings.
Reduced driving range: A struggling thermal system forces the car to use more energy to regulate temperature, eating into your battery’s range.

That’s why a proper bleed—especially using a professional diagnostic tool like the LAUNCH X431—is essential after any coolant system repair or component replacement.

Tools and Prerequisites

Before starting, gather the following items and ensure you have the right conditions:

Tool / Item	Purpose
LAUNCH X431 diagnostic scanner	Activates the electric water pump and runs the bleed program
Coolant (Kia EV4 spec: pink, ethylene-glycol based, low-conductivity)	Topping off after air removal
Personal protective equipment (gloves, safety glasses)	Protect against hot coolant and contact with high-voltage components
Coolant catching container & lint-free rags	Catch spillage and clean up
Owner’s manual or service information	Locate bleeder valve positions and confirm coolant type

Important: The Kia EV4 uses a dedicated low-conductivity pink coolant (part number 00119-74080 or equivalent). Never mix colors or use standard green/blue coolant—this can damage the high-voltage battery’s internal insulation.

Step-by-Step Coolant Bleed Procedure Using LAUNCH X431

Follow these steps in order. The LAUNCH X431 will guide you, but this manual walkthrough ensures nothing is missed.

1. Prepare the Vehicle

Park the EV4 on a level surface and turn the vehicle off. Let it sit for at least 30 minutes to cool completely—hot coolant can cause burns.
Carefully remove the coolant reservoir cap. On the EV4, the cap is located near the front of the engine bay, marked with a blue or yellow label. Turn it slowly to release any residual pressure.
Set the LAUNCH X431 to VCI mode (the wireless communication mode) and connect the diagnostic cable to the OBD-II port under the dashboard. The scanner will power on automatically.

2. Access the Bleeding Function

Turn the ignition ON (press the start button without pressing the brake to enter “Ready” mode). The instrument cluster will light up, but the motor will not run.
On the LAUNCH X431, launch the diagnostic software. Select Kia from the vehicle menu, then choose K9 (EV4). If you see multiple model years, select the one that matches your vehicle (typically 2024+).
Navigate to Diagnosis → Electric/Hybrid Control → Coolant Bleeding. On some software versions, this may be under Active Diagnostics or Special Functions. If you cannot find it, ensure your LAUNCH X431 has the latest software update.
The scanner will prompt you to confirm the coolant level. Do not skip this—if the reservoir is low, add coolant to the “MIN” line before proceeding.

3. Perform the Bleed Cycle

Once the scanner begins the bleed procedure, it will command the electric water pump to run at high speed. You will hear a faint whirring sound from the front of the engine bay.
Turn the cabin heater ON to maximum temperature and set the fan to low. This opens the heater core valve and allows coolant to circulate through the entire heating loop.
Let the pump run for 3–5 minutes. During this time, air bubbles will be pushed toward the highest point in the cooling system—usually the bleeder valve or the reservoir.

4. Manual Bleeding (If Equipped)

The Kia EV4 cooling system typically includes a manual bleeder valve located on the heater hose or near the coolant reservoir top hose. Check your owner’s manual for the exact location.

While the pump is still running (keep the LAUNCH X431 on the same screen), locate the bleeder valve.
Using a wrench or screwdriver (size depends on the valve type), slowly open the valve. You will see a mix of coolant and air bubbles escape.
Continue until the escaping coolant runs clear and steady with no visible bubbles. This may take 10–20 seconds.
Immediately close and tighten the valve to prevent coolant loss.

Tip: Place a rag or small container under the valve to catch drips—coolant can damage painted surfaces.

5. Top Off and Recheck

With the pump still running (or after the first cycle stops), add coolant to the reservoir until it reaches the MAX fill line.
On the LAUNCH X431, select “Run Cycle Again” (or “Repeat” depending on the interface). This second cycle typically runs for 5 minutes and ensures all remaining air is pushed out.
Watch the scanner for a “Bleed Complete” message. If you do not see it, repeat the manual bleed step.

6. Verify System

Turn the ignition OFF, then replace the coolant reservoir cap securely.
Start the vehicle (press brake and start button for normal “Ready” mode) and let it idle for a few minutes.
Turn the heater to maximum heat and medium fan speed. Warm air should flow within 1–2 minutes.
Inspect the bleeder valve and nearby hoses for leaks. Wipe away any spilled coolant.
Finally, clear any diagnostic trouble codes (DTCs) using the LAUNCH X431. Go to Diagnosis → Read DTCs and erase any codes related to cooling system faults—they will not reappear if the bleed was successful.

Common Troubleshooting Issues

Problem	Likely Cause	Solution
Scanner does not find bleed function	Outdated software or wrong vehicle model	Update LAUNCH X431 to latest version; double-check VIN (Kia EV4 VINs start with KNAGH)
Pump runs but no coolant flow	Air lock in pump or hose	Jiggle the coolant hoses gently; raise the front of the vehicle slightly with a jack to help air escape
Bleeder valve is stuck	Corrosion or debris	Tap the valve gently with a wrench; apply penetrating oil only if safe (avoid getting oil on belts or hoses)
Overheating after bleed	Air still trapped	Repeat the entire bleed cycle; check for system leaks around hoses and the battery chiller
Heater blows cold after bleed	Insufficient coolant level or air in heater core	Top off reservoir again; run a third bleed cycle with heater on full

Important Safety Precautions

Working with an electric vehicle demands extra caution. Follow these every time:

High-voltage components: Never touch orange cables, connectors, or the battery pack itself. The LAUNCH X431 only interacts with the 12V system—the high-voltage system remains isolated.
Hot coolant: Even after 30 minutes of cooling, coolant can be hot enough to cause burns. Use gloves and open caps slowly.
Proper disposal: Collect all drained coolant in a sealable container. Antifreeze is toxic to pets and the environment—dispose of it at a local recycling center or auto parts store that accepts used coolant.
Bleeder valve location: If you cannot find the valve, do not force any component. Some EV4 models may not have a manual bleeder—in that case, rely entirely on the LAUNCH X431’s automated cycle.

FAQ

Q: How often should I bleed the coolant on a Kia EV4? A: You should perform a coolant bleed after any repair that opens the cooling system (replacing the heater, water pump, battery chiller, or hoses). Also, if you notice weak heater performance or the dashboard warns of coolant temperature issues, a bleed is a good first step. The LAUNCH X431 can also run a diagnostic check to confirm if air is present.

Q: Do I need to run the engine during the bleed procedure? A: No, the Kia EV4’s electric water pump runs on 12V power and is activated by the LAUNCH X431 command. You only need the ignition on (Ready mode) so the pump receives power. The motor stays off the entire time.

Q: What type of coolant does the Kia EV4 use? A: Kia specifies an ethylene glycol-based pink coolant with low conductivity (part number 00119-74080 or equivalent). This formula is designed to prevent electrical leakage within the battery’s cooling channels. Never mix with other colors or standard green coolant.

Q: Can I bleed the coolant without a LAUNCH scanner? A: Not effectively. The EV4’s water pump is electric and requires a scan tool to command it to run. A manual bleed (opening the valve without pump activation) cannot push air out of the closed battery cooling loop. The LAUNCH X431 is the easiest way to ensure a complete bleed.

Q: The LAUNCH X431 says “Bleed Complete” but the heater still isn’t working. What next? A: Check the coolant level again—it may have dropped as air worked its way out. Also inspect for leaks around the heater core or hoses. If level and leaks are fine, the heater relay or fuse may be faulty. In rare cases, a full factory manual bleed (including high-voltage system re-calibration) may be required. For this, consult a Kia dealership.

Final Checklist After Bleed

Coolant reservoir filled to MAX line.
No leaks at bleeder valve, hoses, or reservoir cap.
Heater produces warm air within 2 minutes of turning on.
No warning lights on dashboard related to cooling or battery temperature.
LAUNCH X431 shows no DTCs in the Electric/Hybrid Control module.

About the Author: Erwin Salarda is an Automotive Service Equipment Technician based in the Philippines, specializing in computerized automotive diagnostic equipment such as OBD scanners and wheel alignment systems. Since 2012, he has been actively providing technical support, equipment installation, troubleshooting, after-sales service, and hands-on training for automotive service equipment used by workshops and automotive professionals.

He has received specialized training from international suppliers and manufacturers, including Launch X431 in Shenzhen, China, Lawrence Engineering Company in Guangzhou, China, and 3Excel Wheel Alignment Company in Shenzhen, China. Through these trainings, he developed advanced expertise in automotive diagnostics, calibration, wheel alignment systems, and computerized automotive service technologies.

Erwin Salarda provides professional after-sales support and technical training for automotive diagnostic and wheel alignment equipment, helping clients maximize the performance and proper use of their tools and systems. His experience covers equipment setup, software updates, calibration procedures, troubleshooting, and operational guidance for automotive workshops and service centers.

With more than a decade of experience in the automotive equipment industry, Erwin Salarda continues to support automotive businesses by delivering reliable technical expertise and practical training solutions.

For inquiries and equipment purchases, please visit https://carlifterph.com/

For more information on using diagnostic tools for other electric vehicle maintenance tasks, check out our guide on [link to related guide on EV battery diagnostics].