E52 DC bus voltage out of range

What the control is telling you

The DC bus voltage on the outdoor unit is too high or too low.

Applies to: Bosch IDS Light BOVA15-24/36/60 and IDS Premium Connected BOVA36-20/60-20 R-454B heat pump outdoor units

Likely causes

• Supply voltage out of range (aim for 187-253 VAC)
• Wrong input wiring
• Shorted compressor or fan motor
• Control board fault

Test and repair steps

1. Warning: Switch off power and wait 3 minutes before measuring resistance or touching boards.
2. Verify supply wiring and voltage between 187 and 253 VAC.
3. Check compressor windings U/V/W (under 1 ohm between phases, over 1 Mohm to ground).
4. Check fan motor windings and replace motor or compressor if failed.
5. Replace the outdoor control board if the fault shows in standby.

Models that show this code

5 models in Bosch IDS Light, Bosch IDS Premium Connected

Other codes on the same units

• E43 T4 temperature sensor fault
• E44 T5 temperature sensor fault
• E45 Th temperature sensor fault
• E51 Input voltage out of range
• E81 EEV coil fault
• F1 High pressure switch protection
• F2 System lockout (5 low-pressure trips in 100 minutes)
• F4 Pressure transducer fault