When a Bosch heat pump stops on a fault, it shows a code: on a small display inside the outdoor unit for Bosch IDS ducted systems, or on the indoor unit for Bosch Climate 5000 mini splits. This guide lists the Bosch heat pump error codes for both families, what they mean, which ones aren’t faults at all, how to reset the system and what the usual repairs cost.
The definitions come from Bosch’s own installation and service manuals for the IDS outdoor units (BOVA, BOVB, BOVC and BOVD series), the IDS Light R-454B condensing unit, the IDS Premium air handler and the Climate 5000 wall-mounted mini splits, Generations 2 to 4. Bosch reuses some codes with different meanings across these families, so start by working out which one you have.
Table of Contents
Which Bosch system do you have?
- Bosch IDS (Inverter Ducted Split). A ducted heat pump with an outdoor unit and an indoor air handler or furnace. Codes appear on a two-digit display on the outdoor unit’s control board. The older R-410A models are the BOVA, BOVB, BOVC and BOVD series; the newer R-454B models include the IDS Light BOVB15 and the IDS Premium.
- Bosch Climate 5000 mini split. A ductless wall unit. Generation 2 (model numbers ending in A or B) shows two-character codes such as E1 or P4. Generation 3 (C models) and Generation 4 (R-454B) show four-character codes such as EL01 or PC08.
The same code can mean different things on different Bosch systems. E5 is a power supply voltage fault on an IDS outdoor unit but an indoor coil sensor fault on a Climate 5000 Gen 2. P1 is the high-pressure switch on IDS but a voltage problem on Climate 5000 Gen 2. Check your model number on the unit’s rating plate before you look up a code.
Codes and displays that aren’t faults
- dF means the system is defrosting, on both IDS and Climate 5000. On mini splits the fans stop while the compressor keeps running, and white mist afterwards is normal.
- A number on the IDS display is normal: the outdoor temperature in standby, or the compressor speed in hertz while it runs.
- A letter in front of the speed (L, D, P, F, C, U or A on IDS) means the unit is running in a limited mode to protect itself, for example to return oil to the compressor.
- AtL on IDS means the outdoor temperature is outside the normal operating range. The unit limits itself until conditions ease.
- CL and nF on Climate 5000 Gen 4 are filter reminders: clean the filter, or replace it.
- LC and LH codes on Climate 5000 Gen 3 and 4 are speed limits, not failures.
- A 3-minute delay before the compressor restarts is normal protection.
Bosch IDS error codes (R-410A outdoor units)
These apply to the BOVA15, BOVA20, BOVB20, BOVC20 and BOVD20 outdoor units.
| Code | What it means |
|---|---|
| C3 | Outdoor coil sensor (T3) not reading correctly in cooling |
| E4 | Temperature sensor fault (outdoor coil, outdoor air, discharge or board sensor) |
| E5 | Supply voltage too high or too low |
| E6 | Outdoor DC fan motor fault |
| E7 | Discharge temperature sensor not seated |
| E9 | Memory chip (EEPROM) fault |
| H0 | Communication fault inside the main control |
| H5 | Lockout after 5 low-pressure events in 100 minutes; needs a power reset |
| H8 | Pressure transducer fault |
| P0 | Inverter module or control board too hot |
| P1 | High-pressure switch tripped |
| P2 | Low pressure, in cooling or heating |
| P3 | Compressor overcurrent |
| P4 | Discharge temperature too high |
| P5 | Outdoor coil too hot in cooling |
| P8 | Fan protection in high wind |
| PH | Low discharge superheat |
| F1 | High-pressure switch fault |
| L0–L9 | Inverter module (IPM) protection |
Bosch’s own troubleshooting page also pairs some codes differently, such as P0/F4 for a high outdoor coil temperature. These seem to come from older firmware, so when the page and your manual disagree, go by the manual for your exact model.
Bosch IDS Light R-454B codes (BOVB15)
The newer R-454B IDS Light uses an expanded code set. The main ones:
| Code | What it means |
|---|---|
| b2 | Indoor coil sensor (T2) fault |
| b3, b4 | Refrigerant sensor hardware or wiring fault |
| b5 | Indoor and outdoor units not communicating |
| b7 | Refrigerant leak detected |
| b8 | Refrigerant sensor past its service life |
| b9 | Refrigerant sensor DIP switch set wrong; needs a power reset |
| bF | Furnace fault |
| Eb | DIP switch setting doesn’t match the unit type |
| E41–E44 | Outdoor coil, outdoor air or discharge sensor fault |
| E51, E52 | Supply voltage or DC bus voltage fault |
| E81 | Expansion valve coil fault |
| F2 | Lockout after 5 low-pressure events in 100 minutes; needs a power reset |
| F4 | Pressure transducer fault |
| P11 | High pressure in heating |
| P21 | Low pressure in cooling |
| P31, P32 | Outdoor or compressor overcurrent |
| P4, P5, PH | Discharge temperature, coil temperature or superheat protection |
| J and n codes | Compressor drive (J) or fan drive (n) faults |
Note that the same faults have new names on R-454B units: the low-pressure lockout is F2 instead of H5, and the pressure transducer is F4 instead of H8.
IDS Premium R-454B air handler light
The IDS Premium air handler has a status light. Steady means normal. Continuous flashing means a refrigerant leak: the blower goes to full speed and the compressor stops. Bosch says not to use the system until a technician has confirmed the repair. Other flash counts point to a sensor or communication fault.
Bosch Climate 5000 Gen 2 codes (A and B models)
On indoor units without a code display, count the flashes of the RUN lamp and check whether the TIMER lamp is off, lit or flashing.
| Code | What it means | RUN flashes / TIMER lamp |
|---|---|---|
| E0 | Indoor memory (EEPROM) fault | 1 / off |
| E1 | Indoor and outdoor units not communicating | 2 / off |
| E3 | Indoor fan speed fault | 4 / off |
| E4 | Room temperature sensor fault | 5 / off |
| E5 | Indoor coil sensor fault | 6 / off |
| EC | Low refrigerant or leak detected | 7 / off |
| F0 | Outdoor overcurrent | 1 / lit |
| F1 | Outdoor air sensor fault | 2 / lit |
| F2 | Outdoor coil sensor fault | 3 / lit |
| F3 | Discharge sensor fault | 4 / lit |
| F4 | Outdoor memory (EEPROM) fault | 5 / lit |
| F5 | Outdoor fan speed fault | 6 / lit |
| P0 | Inverter module protection | 1 / flashing |
| P1 | Voltage too high or too low | 2 / flashing |
| P3 | Outdoor temperature too low | 4 / flashing |
| P4 | Compressor drive fault | 5 / flashing |
| P5 | Mode conflict between indoor units | 6 / flashing |
Bosch Climate 5000 Gen 3 and Gen 4 codes
These four-character codes are shown on the indoor display. The first letter tells you the type: E for error, P for protection, F for faulty and L for a speed limit. The second letter tells you where: H for the indoor unit, C for the outdoor unit and L for other.
| Code | What it means |
|---|---|
| EH00, EH0A | Indoor memory (EEPROM) fault |
| EH03 | Indoor fan speed fault |
| EH60, EH61 | Room sensor or indoor coil sensor fault |
| EH0b | Indoor board and display not communicating |
| EL01 | Indoor and outdoor units not communicating |
| EL0C | Low refrigerant or leak |
| EC51 | Outdoor memory (EEPROM) fault |
| EC52, EC53, EC54 | Outdoor coil, outdoor air or discharge sensor fault |
| EC07 | Outdoor fan speed fault |
| PC00 | Inverter module protection |
| PC02 | Compressor top temperature protection |
| PC03 | Pressure protection |
| PC08 | Outdoor overcurrent |
| PC10, PC11 | Low or high supply voltage |
| PC40 | Outdoor drive communication fault |
| PC0L | Outdoor temperature too low |
| PH90, PH91 | Indoor coil too hot or too cold |
| EHC1, EHC2 | Refrigerant leak detected (Gen 4) |
| EHC3, ECC1, FHCC | Refrigerant sensor or other-zone leak alerts (Gen 4) |
On Gen 3 units you can also bring up the last code with the remote: hold ON/OFF and Fan Speed together for about 7 seconds.
Refrigerant leak codes: stop and call
The newer R-454B systems carry refrigerant sensors. If yours shows a leak code (b7 on IDS Light, continuous flashing on the IDS Premium air handler, or EHC1 or EHC2 on a Climate 5000 Gen 4), keep the system off and call a licensed technician. The Gen 4 owner’s manual says the unit beeps for five minutes when it detects a leak. Bosch also tells owners to stop and call for service right away if they smell burning or a breaker keeps tripping.
How to reset a Bosch heat pump
- IDS: Bosch’s troubleshooting page says to switch off the outdoor disconnect until the display goes blank, then restore power. H5, F2 and b9 always need this power reset.
- Climate 5000: turn the unit off, switch off its breaker and wait. The Gen 4 owner’s manual says 10 seconds; Bosch’s service manuals say 2 minutes, so waiting the longer time does no harm.
Reset once. If the same code comes back, the cause is still there. H5 and F2 in particular mean low pressure has tripped five times in under two hours, which usually points to a refrigerant or airflow problem that a reset won’t fix.
What you can safely check yourself
- The air filter. Bosch asks owners of IDS air handlers to check the filter every 90 days and never run the system without one.
- The outdoor coil. Clear leaves and snow and gently hose off the coil with the power off. Dirty coils and filters are among the causes Bosch lists for P1, P3, P4 and PH.
- The weather. For P8 (high wind) and AtL (extreme outdoor temperature), Bosch suggests waiting for conditions to ease and seeing whether the code returns.
- Defrost. dF, a pause in heating and steam from the outdoor unit are normal. See our guide to a frozen heat pump if ice builds up and doesn’t clear.
- Cycling. If the system keeps stopping and starting without a code, see our guide to heat pump short cycling.
What Bosch repairs usually cost
| Repair | Likely codes | Typical cost |
|---|---|---|
| Filter, clearing the outdoor unit | P1, P3, P4, PH | Little or nothing if you do it |
| Service call or diagnostic | Any | $75–$250 |
| Temperature sensor or control board | E4, E41–E44, F1–F3, EC52–EC54, E9 | Less for a sensor; $150–$700 for a board |
| Outdoor fan motor | E6, F5, EC07 | $200–$700 |
| Refrigerant leak repair | H5, F2, P2, P21, EC, EL0C, b7 | $200–$1,500, plus refrigerant |
| Compressor | P3, P4 (once other causes are ruled out) | $650–$3,500 |
Ranges come from Fixr (January 2026), HomeAdvisor (June 2026) and Angi (October 2026). Bosch’s own bulletin for the BOVA15 says an E6 code most often traces to the control board rather than the fan motor, so ask for that to be checked first.
Is it covered by the warranty?
- IDS heat pumps (warranty effective July 2025): 10 years on the compressor and internal parts for residential installs, excluding the gateway. Labor is covered for 90 days if the system is registered within 90 days. The warranty is void if a licensed HVAC contractor didn’t install it.
- Climate 5000 R-454B mini splits (effective July 2024): 10 years on the compressor; 7 years on parts, or 10 years if registered within 90 days. Labor is covered for 90 days only when an Accredited Bosch Pro contractor registers the system.
Homeowners can register at boschprohvac.com/register. Check your registration before you pay for a part.
Frequently asked questions
Where is the error code on a Bosch heat pump?
On Bosch IDS ducted systems, it’s on a two-digit display on the control board inside the outdoor unit, which a technician reads. On Climate 5000 mini splits, it appears on the indoor unit’s display or as a count of flashing lamps.
What does dF mean on a Bosch heat pump?
dF means the heat pump is defrosting its outdoor coil. It’s normal in heating mode and clears on its own.
What does H5 mean on a Bosch IDS?
H5 is a lockout after five low-pressure events within 100 minutes. It needs a power reset, but if it returns the system usually has a refrigerant or airflow problem that needs a technician. On newer R-454B IDS Light units the same lockout is called F2.
What does EL0C or EC mean on a Bosch mini split?
Both point to low refrigerant or a leak on a Climate 5000 mini split. Refrigerant isn’t used up, so a technician needs to find and repair the leak.
How do I reset a Bosch heat pump?
Switch off the power at the outdoor disconnect or breaker until the display goes blank, wait a couple of minutes, then restore it. If the same code comes back, call a technician.
Sources
- Bosch, IDS BOVA20 and BOVC20 installation instructions (December 2023)
- Bosch, IDS Heat Pump Light Series condensing unit installation manual (July 2026)
- Bosch, IDS Premium Series air handler installation manual (February 2026)
- Bosch Home Comfort, Troubleshoot air-to-air heat pump systems
- Bosch, IDS BOVA15 E6 error troubleshooting bulletin (July 2025)
- Bosch, Climate 5000 Gen 2 ductless outdoor unit service manual (May 2025)
- Bosch, Climate 5000 Gen 3 wall-mounted service manual (May 2025)
- Bosch, Climate 5000 Gen 4 wall-mounted service manual (May 2025)
- Bosch, Climate 5000 Gen 4 wall-mounted user manual (April 2026)
- Bosch, Inverter Heat Pump Product Family Limited Warranty (November 2025)
- Bosch, Climate 5000 Gen 4 mini split warranty (November 2024)
- Fixr, Heat Pump Repair Cost (January 2026)
- HomeAdvisor, Heat Pump Repair Cost (June 2026)
- Angi, Heat Pump Repair Cost (October 2026)