E4 on a Kensa heat pump: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor
Short answer
On a Kensa heat pump, E4 means: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 11 sources
What it means
On the Compact (single compressor)
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the Twin Compressor Compact
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the Evo
The manual says: T4 temperature probe error (ground flow).
Part involved: T4 ground flow probe.
When it shows: Error level per manual: Fault.
Likely causes:
- T4 probe faulty or disconnected.
On the High Temperature Compact
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the High Temperature Plantroom
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the Hybrid Twin Compressor
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the Plantroom
The manual says: Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
Part involved: Temperature probe / weather compensation sensor.
When it shows: Legacy panel controller: 'Display flashes fault code E4'.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
On the Q80 Series (Kensa Q)
The manual says: T4 temperature probe error (ground flow).
Part involved: T4 ground flow probe.
When it shows: Error level per manual: Fault.
Likely causes:
- T4 probe faulty or disconnected.
On the Shoebox
The manuals for this range word it in different ways:
- Loss of contact with a probe; E4 could be loss of contact with the weather compensation sensor.
- T4 temperature probe error (ground flow).
Part involved: Temperature probe / weather compensation sensor; T4 ground flow probe.
When it shows: Legacy panel controller: 'Display flashes fault code E4'. Error level per manual: Fault.
Likely causes:
- Probe or weather compensation sensor disconnected or faulty.
- T4 probe faulty or disconnected.
On the Shoebox NX
The manual says: T4 temperature probe error (ground flow).
Part involved: T4 ground flow probe.
When it shows: Error level per manual: Fault.
Likely causes:
- T4 probe faulty or disconnected.
Is it safe?
On the Compact (single compressor)
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Twin Compressor Compact
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Evo
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
On the High Temperature Compact
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the High Temperature Plantroom
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Hybrid Twin Compressor
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Plantroom
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Q80 Series (Kensa Q)
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
On the Shoebox
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
On the Shoebox NX
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Note the code shown on the controller/LED; check the heat pump isolator and consumer-unit breaker are on; check thermostat/timer settings.
What the engineer will check
On the Compact (single compressor)
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the Twin Compressor Compact
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the Evo
- Follow Kensa fault table actions: T4 probe faulty or disconnected.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended; Kensa-trained.
On the High Temperature Compact
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the High Temperature Plantroom
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the Hybrid Twin Compressor
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the Plantroom
- Check probe connections/continuity; refer to Kensa Technical department.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended.
On the Q80 Series (Kensa Q)
- Follow Kensa fault table actions: T4 probe faulty or disconnected.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended; Kensa-trained.
On the Shoebox
- Check probe connections/continuity; refer to Kensa Technical department.
- Follow Kensa fault table actions: T4 probe faulty or disconnected.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended; MCS-certified GSHP installer recommended; Kensa-trained.
On the Shoebox NX
- Follow Kensa fault table actions: T4 probe faulty or disconnected.
Who to ask for: Heat pump controls engineer / Kensa technical support.
Certification: MCS-certified GSHP installer recommended; Kensa-trained.
What you might notice
Sources
- Single Compressor Compact Heat Pump Manual ↗ · Version 11 · page 41 · Reviewed 23 September 2026
- Twin Compressor Compact Heat Pump Manual ↗ · Version 14 · page 38 · Reviewed 23 September 2026
- Kensa Evo Heat Pump Installation manual ↗ · V32 · page 52 · Reviewed 23 September 2026
- High Temperature Single Compressor Compact Heat Pump Manual ↗ · Version 5 · page 41 · Reviewed 23 September 2026
- High Temperature Plant Room Heat Pump Manual ↗ · v4.1 · page 30 · Reviewed 23 September 2026
- Hybrid Twin Compressor Compact Heat Pump Manual ↗ · Version 4 · page 38 · Reviewed 23 September 2026
- Plant Room Heat Pump Manual ↗ · Version 11.1 · page 30 · Reviewed 23 September 2026
- Q80 Series Heat Pump Operational Manual ↗ · Version 2 · page 25 · Reviewed 23 September 2026
- Shoebox Heat Pump Installation and Commissioning Manual (ground array) ↗ · Version 4 · page 33 · Reviewed 23 September 2026
- Shoebox Heat Pump Operational Manual (User Manual) ↗ · Version 8 · page 28 · Reviewed 23 September 2026
- Kensa Shoebox NX heat pump Installation manual ↗ · V12 · page 42 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026