Bosch HP270-2 Technical Manual page 47

Code E08 * – Lock Out Error (reset by pressing OK for more than 3 sec)
Fault in the pocket (middle of tank) NTC temperature sensor
* Note: external system must be active (Boiler or Solar) in order to allow display of this error. Error is only displayed 2 min after the condition is
detected by control unit.
In case external system accessory is not installed or HP model without coil, check if "boil" or "sol" mode were not activated accidentally.
The NTC sensor is
interrupted or in short
circuit
Refer to table with
values in Service
Manual
See spare part list
See spare part list
Page 47 from 56
Ensure NTC connection wire is
correctly plugged in accessory box
Ensure connection cable from
accessory box is connected to the
control unit
Unplug connection and Measure the
NTC electrical resistance [R] (Ω)
[R] > 55 kΩ or < 0.68 kΩ
Yes
NTC value out of
range
Replace NTC
Plug NTC connection
wire and turn ON unit
Problem solved?
No
Change accessory
box
Problem solved?
No
Replace control unit
6-720-821-364 SM HP270 – 250 - 200 2016/12 en
ATTENTION:
NTC systems (Coil / Tank)
[R] = ∞ Ω
Yes
NTC interrupted
No
Yes
End
Yes
No