Baxi Baxi 200/400/600/800 Combi 2 & System 2 Baxi 600/800/Assure System 2 and 600 Combi 2 platform fault H.01.05
Maximum temperature difference value between flow and return reached
Gas boilerWhat it means
The temperature differential between flow and return has exceeded the maximum permitted value, indicating insufficient circulation or sensor issues.
Likely causes
- Insufficient boiler/installation circulation
- Low installation pressure
- Dirty heat exchanger
- Faulty temperature sensors
- Poor temperature sensor connection
Where to start
- Check the boiler/installation circulation
- Check the installation pressure
- Check the cleanliness of the exchanger
The full answer, free
- 13 more checks in order
- The readings and component tests from the manual
- How to put it right, step by step
- The manual page for this fault (page 71), right under the answer
Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.
From the Baxi manual for the Baxi 200/400/600/800 Combi 2 & System 2 Baxi 600/800/Assure System 2 and 600 Combi 2 platform. Check the model on the data plate before you order parts.
Other Baxi Baxi 200/400/600/800 Combi 2 & System 2 Baxi 600/800/Assure System 2 and 600 Combi 2 platform fault codes
- A.00.34Outdoor temperature sensor expected but not detected
- A.02.06Low water pressure
- AC004Failed start-up attempts after last maintenance
- DC004Number of burner start-ups for DHW mode
- DC005Number of burner start-up hours for DHW mode
- E.01.04Flame loss detected five times in 24 hours (with burner on)
- E.01.12Temperature measured by return sensor greater than flow temperature
- E.01.17No water circulation (permanent)
- E.01.20Maximum flue gas temperature reached
- E.04.08Maximum safe temperature value reached
- E.04.10Burner failed to ignite after 4 attempts
- E.04.11VPS gas valve test failed
- E.04.12Ignition failure for monitoring parasitic flame
- E.04.14Temperature difference between set point and burner varies more than 60s compared to...
- E.04.15Flue gas exhaust pipe blocked
- E.04.17Fault in gas valve control circuit
- E.04.23Gas valve check valve internal stoppage
- E.04.24Gas family not detected during the automatic detection function
- E.04.54Fault in gas valve control circuit
- GC007Failed start-up attempts
- H.01.08Flow temperature increase in heating mode too quick (10 minute stoppage)
- H.01.18No water circulation (temporary)
- H.01.21Flow temperature increase in domestic water mode too quick (10 minute stoppage)
- H.02.09Partial stoppage of the boiler, signal indicating blocking input active or frost...