Air Conditioner
Walton
Updated Jul 25, 2026
Walton AC E4 Error — Indoor Room Temperature Sensor Fault & Fix
E4
Walton · Air ConditionerE4 on a Walton AC means the indoor room temperature sensor (return-air thermistor) has an…
Quick answer
E4 on a Walton AC means the indoor room temperature sensor (return-air thermistor) has an open or short circuit.
What E4 means
The room sensor is a small thermistor near the air-return grille inside the indoor unit. It measures room temperature so the board can control the compressor and reach the set temperature. When this sensor fails (open or shorted), the board cannot regulate cooling and displays E4.
How to fix it
- Power off at the breaker.
- Open the indoor panel and locate the room sensor — a small bead or capsule near the return-air grille, connected by two wires to the PCB.
- Reseat the connector at the PCB. This is the most common fix — the plug has vibrated loose.
- Test with a multimeter — at 25°C, expect approximately 10 kOhm. Open (OL) or zero means the sensor is dead.
- Replace if faulty. Room sensors are inexpensive and available at Walton service centres.
What does the E4 code mean?
E4 indicates the indoor room temperature sensor (thermistor) has an open or short circuit. The board cannot measure room temperature.
Common causes
- Loose sensor connector on the indoor PCB (most common)
- Failed thermistor (open or short circuit)
- Damaged wiring
- PCB sensor input circuit fault (rare)
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How to fix the E4 error
Power off
Isolate at the breaker.
Locate the room sensor
Near the return-air grille, two-wire lead to PCB.
Reseat the connector
Unplug and re-plug firmly.
Test with multimeter
Approximately 10 kOhm at 25 degrees C.
Replace if faulty
Match the thermistor to your Walton model.
Safety first: Isolate power before opening the indoor unit.
Part you may need: Indoor room temperature sensor (NTC 10 kOhm thermistor)
Available at Walton Plaza service centres or order through waltonbd.com support.
Frequently asked questions
Is E4 easy to fix?
Yes — reseating the connector fixes most E4 cases. Sensor replacement is simple and inexpensive.
Can a dirty filter cause E4?
No — E4 is an electrical sensor fault, not an airflow issue.
✎ Written by
REZAUL Karim (Riad)
REZAUL Karim (Riad) is the founder of ErrFixHub and a hands-on electronics and home-appliance repair specialist with over 15 years of experience diagnosing and fixing air conditioners, washing machines, refrigerators, inverters and other household appliances. He built ErrFixHub to turn cryptic error codes into clear, step-by-step fixes anyone can follow — cross-checking every code against manufacturer documentation and real repair-bench experience.
