E00.00 on a Baxi heat pump: TFlow Open Flow temperature sensor is either removed or measures a temperature below range
Short answer
On a Baxi heat pump, E00.00 means: TFlow Open Flow temperature sensor is either removed or measures a temperature below range. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
On the Assure Split ASHP (AWHP 4.5/6/8 MR + Assure AWHP-IDU 4-8 E)
The manual says: TFlow Open Flow temperature sensor is either removed or measures a temperature below range.
Part involved: temperature sensor.
On the HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP (R290)
The manual says: TFlow Open Flow temperature sensor is either removed or measures a temperature below range.
Part involved: temperature sensor.
Likely causes:
- Poor sensor connection: Check the wiring between the PCB and the sensor Check that the sensor has been correctly fitted Sensor failure: Check the Ohmic value of the sensor Replace the sensor if necessary.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Remove cause, then acknowledge the error manually on the user interface (engineer).
What you can check
- Note the exact code shown on the controller and when it appeared.
- The manual's user steps allow switching the system off and on once to see if the error clears; if the code returns, contact the installer.
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
On the Assure Split ASHP (AWHP 4.5/6/8 MR + Assure AWHP-IDU 4-8 E)
- Diagnose per manufacturer service procedure (manual gives description only).
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
On the HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP (R290)
- Poor sensor connection: Check the wiring between the PCB and the sensor Check that the sensor has been correctly fitted Sensor failure: Check the Ohmic value of the sensor Replace the sensor if necessary.
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
What you might notice
Sources
- Installation and Service Manual - Air/water 'Split Inverter' heat pump Baxi Assure, Assure AWHP-IDU 4-8 E ↗ · 7762758 - v05 - 19082020 · page 93 · Reviewed 23 September 2026
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 134 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026