E4 Error on Mitsubishi MSZ-GL15NA Mini Split — Fix Guide

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• Source: Official Mitsubishi service manual
• Reviewed by: Geo Technical Editorial
• Published: March 1, 2026
• Updated: March 1, 2026

Safety notice: Start with user-safe checks only. Do not open sealed refrigerant systems, inspect gas-train components, or work on energized high-voltage parts unless you are qualified to service this appliance.

Error E4 on Mitsubishi : Low pressure / refrigerant shortage detected. Follow the troubleshooting steps below to diagnose and fix this mini-split issue. ## What Error Code E4 Means on a Mitsubishi MSZ-GL15NA Error E4 on the MSZ-GL15NA indicates suction-side pressure has fallen below the safe threshold, typically caused by refrigerant leakage, a blocked filter, or a malfunctioning expansion valve. When E4 appears, the Mitsubishi mini split pauses normal operation to protect internal components from potential damage. Not every E4 fault requires a professional engineer — many are resolved through careful inspection and routine maintenance. Work through each diagnostic step below in sequence, starting with the simplest check, to identify the root cause efficiently before considering part replacement or arranging a service call. ## Symptoms - Indoor unit blows warm air in cooling mode

• Ice forming on indoor coil or refrigerant lines
• Compressor hums but system won’t cool
• E4 blinks on display ## Common Causes - Low pressure / refrigerant shortage detected ## Tools You May Need - Manifold gauge set
• Electronic leak detector
• Flashlight ## Step-by-Step Repair Guide | Step | Action | Result | |------|--------|--------| | 1 | Switch the system off immediately to prevent compressor damage from running with low refrigerant. | Done — continue to step 2 if the issue persists. | | 2 | Inspect the indoor air filter — a severely clogged filter can cause coil freeze and apparent low pressure. | Done — continue to step 3 if the issue persists. | | 3 | Check all accessible refrigerant line fittings, flare connections, and service valves for oily residue indicating a leak. | Done — continue to step 4 if the issue persists. | | 4 | If filter is clean and no visible leaks are found, contact a licensed HVAC technician to perform a leak test and recharge the system. | Done — continue to step 5 if the issue persists. | | 5 | Do not simply add refrigerant without finding and repairing the leak first. | Done — if the fault remains, contact a qualified technician. | ## Safety Precautions Refrigerant handling requires EPA Section 608 certification. Do not release refrigerant into the atmosphere. ## Estimated Repair Time and Difficulty Most mini split error code E4 faults can be assessed and addressed in 30–90 minutes using the steps above. The diagnostic process requires only basic tools: a multimeter and standard screwdrivers cover the majority of checks described here. If a replacement part is required, allow 1–5 working days for delivery. A trained technician with access to the correct diagnostic equipment will typically resolve this type of fault within a single service visit. ## When to Call a Technician Contact a Mitsubishi authorised service technician if: the fault persists after following all the steps above; if PCB-level or refrigerant-circuit work is required; or if you are not comfortable working with electrical or mechanical components. When calling, have the full model number, the error code displayed, and a brief description of any sounds or symptoms you noticed before the fault appeared — this helps the technician prepare the correct parts and tools. ## Frequently Asked Questions Q: Why does E4 cause ice on the coil? Low refrigerant causes the coil to run at very low temperature, freezing any moisture in the air that passes over it. This further blocks airflow and worsens the fault. Q: How much refrigerant does a Mitsubishi mini-split hold? Pre-charged systems hold approximately 0.6–1.8 kg of R-410A depending on BTU capacity. Field-charged systems vary with line length; refer to the installation manual for exact quantities. ### Is it safe to keep using my Mitsubishi with error E4? If error E4 does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the mini-split with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error E4 on a Mitsubishi ? Repair costs for error E4 on the Mitsubishi mini-split depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a Mitsubishi-authorized service provider for an accurate estimate based on your specific situation. ### What does error code E4 mean on a Mitsubishi mini-split? Error code E4 on Mitsubishi mini-split models indicates Low pressure / refrigerant shortage detected. This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue. ### Is it safe to keep using my Mitsubishi with error E4? If error E4 does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the mini-split with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error E4 on a Mitsubishi ? Repair costs for error E4 on the Mitsubishi mini-split depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a Mitsubishi-authorized service provider for an accurate estimate based on your specific situation. ### What does error code E4 mean on a Mitsubishi mini-split? Error code E4 on Mitsubishi mini-split models indicates Low pressure / refrigerant shortage detected. This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue.