Daikin Mini-Split E4 Error Code: Low Pressure Protection

Quick Answer

Daikin E4 is a low pressure protection trip indicating suction pressure has dropped below the safe threshold. On most Daikin residential units, this trips at around 15-20 PSI for R-410A and 10-15 PSI for R-32. Low pressure almost always means refrigerant loss from a leak. Unlike high pressure issues that can be caused by airflow problems, low pressure has limited DIY solutions - the only user-accessible check is ensuring the indoor filter is clean (a severely clogged filter can restrict evaporator airflow enough to drop suction pressure). Beyond that, E4 requires an HVAC technician with gauges to confirm the charge level and perform a leak search.

DaikinMinisplitSeverity: highDifficulty: advanced70% DIY Success

Time to Fix

60–480 min

Difficulty

advanced

Parts Cost

$10 – $150

Tools Needed

Indoor filter cleaning brush, Manifold gauge set (HVAC tech)

What Does the E4 Code Mean?

E4 means low refrigerant pressure, almost always from a refrigerant leak. Clean the indoor filter as a first check, then call an HVAC technician.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Refrigerant leak at flare connections40%

Severely clogged indoor air filter24%

Frozen evaporator coil blocking airflow14%

TXV or EEV valve stuck or failed12%

Restriction in refrigerant circuit (kinked line)10%

Symptoms You May Notice

E4 on indoor display
Ice forming on indoor unit copper connections
Indoor unit blowing warm air before E4
Hissing sound near indoor or outdoor connections
Reduced cooling/heating output over weeks or months

Can you reset a Daikin minisplit to clear the E4 code?

Turn breaker off for 30 seconds. Low pressure switch auto-resets when pressure rises above the cut-in point. If charge is severely low, the switch may not reset until after recharge.

Tools Required for Diagnosis

Indoor filter cleaning brushManifold gauge set (HVAC tech)Electronic leak detectorNitrogen tank

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Turn off the unit

Turn off the unit. Remove and clean or replace the indoor air filters. If the evaporator coil is visible, check for ice buildup. If iced, leave the unit off for 2-4 hours to defrost completely before restarting.

HVAC tech

Perform leak search using electronic refrigerant detector at all

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Indoor air filterModel-specific · $10–$25	Model-specific	$10 – $25
Refrigerant R-410A or R-32N/A · $50–$150	N/A	$50 – $150

Verify part fitment for your Daikin model

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs

Labor Approach

Our Verdict

REPAIR

Estimated Cost: $80 (Parts) vs $5500 (New Machine)

Frequently Asked Questions

Can I add refrigerant to fix E4 myself?

No. Adding refrigerant requires EPA 608 certification by law. More importantly, simply adding refrigerant without finding and fixing the leak means it will leak out again. The proper repair sequence is: find leak, repair leak, vacuum system, then recharge to spec.

My Daikin gets E4 only in heating mode. Why?

In heating mode, the outdoor coil acts as the evaporator. If the outdoor temperature is below the unit's rated minimum (typically 5F to -13F depending on model), the outdoor coil can ice over and cause low suction pressure. A low-ambient kit with a pan heater and pressure controller may be needed.

How much does it cost to fix a refrigerant leak?

A simple flare connection leak repair with recharge typically costs $200-400. A leak in the copper line set requiring brazing is $400-800. An evaporator or condenser coil leak requiring coil replacement is $800-2,000 including refrigerant.

Related Daikin Minisplit Error Codes

Code: HUBDaikin Mini-Split Error Codes: Complete Guide Code: E3Daikin Mini-Split E3: High Pressure Protection Code: U0Daikin Mini-Split U0: Low Refrigerant or Overcurrent Code: F3Daikin Mini-Split F3: Discharge Temp Too High

Models Known to Experience E4 Errors

This repair applies to most Daikin minisplits with this error code. Common model numbers include:

FTXS09LVJU, FTXS12LVJU, FTXM15QVJU, FTXM18QVJU, FTXM24QVJU, RXS09LVJU

Last verified for technical accuracy on March 15, 2026