EA on a Worcester Bosch heat pump: Alarm table: Unit air temperature sensor Tp failure / Troubleshooting table: Tp discharge temperature sensor error
Short answer
On a Worcester Bosch heat pump, EA means: Alarm table: Unit air temperature sensor Tp failure / Troubleshooting table: Tp discharge temperature sensor error. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Bosch Compress 2000 AWF (R32 all-in-one monobloc)
The manual says: Alarm table: Unit air temperature sensor Tp failure / Troubleshooting table: Tp discharge temperature sensor error.
Part involved: Tp compressor discharge temperature sensor.
When it shows: Unit air temperature sensor Tp failure.
Likely causes:
- Sensor connector loose, wet/water ingress in connector, or sensor faulty (manual: reconnect, dry and seal connector with waterproof adhesive, or replace sensor).
On the Greenstar Plus Hybrid (air to water heat pump + Worcester boiler)
The manual says: Control cables between internal and external unit faulty - too many internal units connected.
Part involved: internal-external unit communication.
When it shows: Control cables between internal and external unit faulty - too many internal units connected.
Likely causes:
- Control cable fault >4 min after power on: poor contacts/wiring; control cable sizing (max 30 m, polarity S1/S2/S3); transmitter/receiver circuit faulty in either unit; noise.
Is it safe?
On the Bosch Compress 2000 AWF (R32 all-in-one monobloc)
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: Manual 13.2: switch the unit off and on again to reset the safety device; if reset fails contact dealer. Manual 11.4 warns repeated resets can cause irreversible damage.
On the Greenstar Plus Hybrid (air to water heat pump + Worcester boiler)
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: Codes read via outdoor unit LEDs or service tool 7-716-161-051; SW1-2 DIP switch cancels fault displays (engineer).
What you can check
On the Bosch Compress 2000 AWF (R32 all-in-one monobloc)
- Read and note the full code (and sub-code) shown on the controller and pass it to your installer.
- Manual 13.2: one off/on restart may be tried; if the code returns, stop and call an engineer - repeated resets can damage the unit.
On the Greenstar Plus Hybrid (air to water heat pump + Worcester boiler)
- Read and note the full FW200/hybrid manager fault code shown on the controller and pass it to your installer.
- Check the heat pump isolator and consumer-unit breaker(s) are switched on; if a breaker has tripped more than once, leave it off and call an engineer.
- Check the outdoor unit is not blocked by leaves, snow, ice or other debris (do not open the casing).
What the engineer will check
On the Bosch Compress 2000 AWF (R32 all-in-one monobloc)
- Check sensor connector seating and moisture; measure sensor resistance; replace sensor if faulty (inside unit casing - isolate power, wait 10 min for DC bus discharge).
Who to ask for: F-gas refrigeration engineer / heat pump installer.
Certification: F-gas certification (Category I) required for refrigerant circuit work; qualified electrician for electrical work.
On the Greenstar Plus Hybrid (air to water heat pump + Worcester boiler)
- Control cable fault >4 min after power on: poor contacts/wiring; control cable sizing (max 30 m, polarity S1/S2/S3); transmitter/receiver circuit faulty in either unit; noise.
Who to ask for: heat pump installer / electrician.
Certification: Electrical work to BS 7671 by competent person.
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Keeps stopping / cutting out on the Bosch Compress 2000 AWF (R32 all-in-one monobloc): 1 report
Sources
- Installation and operating instructions Compress 2000 AWF CS2000AWF 4-30 R-S/T ↗ · 6721859133 (2025/10) · page 128; 136 · Reviewed 23 September 2026
- Installation and Maintenance Instructions Greenstar Plus Hybrid ↗ · 6 720 803 687 (2012/11) · page 62 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026