Bosch Error Code E4
Room temperature sensor T1 fault
Error Code Summary
| Brand | Bosch |
| Error Code | E4 |
| Meaning | Room temperature sensor T1 fault |
| Cause | Indoor room thermistor open or short circuit |
| Recommended Action | Check sensor wiring, measure resistance, replace thermistor if faulty |
How to Fix Bosch Error E4
- 1
Power Cycle the Unit
Turn off the unit at the breaker, wait 5 minutes, then restore power. Some errors auto-clear after a restart.
- 2
Identify the Issue
Error E4 means: Room temperature sensor T1 fault. The most common cause is: Indoor room thermistor open or short circuit.
- 3
Take Corrective Action
Check sensor wiring, measure resistance, replace thermistor if faulty
- 4
Test the System
After completing repairs, run the system and monitor for the error code. If it recurs, the issue may require professional diagnosis.
Safety Notice
Always disconnect power before performing any electrical work. If you're not a certified HVAC technician, contact a qualified professional for repairs involving refrigerant, electrical components, or compressor work.
Frequently Asked Questions
What does Bosch error code E4 mean?
Bosch error code E4 indicates: Room temperature sensor T1 fault. This is typically caused by: Indoor room thermistor open or short circuit.
How do I fix Bosch error code E4?
To fix Bosch error code E4: Check sensor wiring, measure resistance, replace thermistor if faulty. If the error persists after these steps, contact a qualified HVAC technician.
Is Bosch error code E4 serious?
Error code E4 (Room temperature sensor T1 fault) should be addressed promptly to prevent further damage to your Bosch system. Always turn off the unit if you notice unusual sounds, smells, or continued malfunction.