Bosch HP270-2 - Troubleshooting - Code E08; E08 - Lock Out Error (Pocket NTC Sensor)

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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
[R] > 55 kΩ or < 0.68 kΩ
[R] = ∞ Ω
NTC value out of
range
NTC interrupted
Replace NTC
Plug NTC connection
wire and turn ON unit
Problem solved?
End
Change accessory
box
Problem solved?
Replace control unit
See spare part list
See spare part list
Refer to table with
values in Service
Manual
Yes
No
No
Yes
No
No
Yes
Yes
ATTENTION:
NTC systems (Coil / Tank)
Ensure NTC connection wire is
correctly plugged in accessory box
Unplug connection and Measure the
NTC electrical resistance [R] (Ω)
Ensure connection cable from
accessory box is connected to the
control unit