LambdaControl 1
Error 26.18
O
2
Sensor
Cause: Error during calibration
Display 4 amber: illuminates
Information text: Limited operation
Emergency program: Controller works only with auxiliary air
Reset: Automatically after error correction and calibration of O
2
sensor.
Error may occur in the following operating status: Only during calibration.
Error detection: During calibration the controller tests the sensor-offset voltage. If it is > -1mV or < -17.5mV, the error message is
displayed.
Rectification: Call service technician – possible causes:
1. Test – wiring harness: Remove the 15-pin plug from the controller. Check for a resistance of <1Ω between the 15-pin plug
(KL4) and plug ST1 (KL2); check for a resistance of <1Ω between the 15-pin plug (KL5) and plug ST1 (KL1). Is that not the case,
the system has a wiring error. In case of a wiring error, continue with test 2.
2. Test – O
2
sensor connection: The grey wire of the O
2
sensor must be connected to plug ST1 (KL1). The black wire of the O
2
sensor must be connected to plug ST1 (KL2). Is that the case, continue with test 3.
3. Test – O
2
sensors: For test purposes replace O
2
sensor and calibrate. If the error is still not rectified after that, the
controller requires replacement.
Experience shows that the controller is usually only defective, if faulty wiring or spurious actions damaged the applicable
input/output.
Controller function: Limited operation with auxiliary air V1-V2. The boiler is deactivated with the function TAG deactivation –
independent from the setting 5.14 Switch-off with “O
2
” or “TAG”.
Note: Fouling of boiler and chimney is possible. With a defective flue gas sensor at the same time, the controller switches OFF
the boiler automatically after 24 hours, or it may be switched off manually (press▼ twice).
LambdaControl 1
Error 26.19
O
2
Sensor
Cause: Sensor used up (operating temperature of O
2
measuring element too low)
Display 4 amber: illuminates
Information text: Sensor used up
Emergency program: The controller works with reduced O
2
measuring accuracy
Reset: Automatically by pressing button ► (refuel)
Error may occur in the following operating status: Only in “Boiler ON”.
Error detection: The controller checks the internal resistance of the O
2
-measuring unit. If it is <500Ω for longer than one hour,
the error message is displayed immediately.
If the internal resistance is >500Ω, it means, that the internal heating of the element is not sufficient to reach the
required temperature. This would lead to significant deviations with higher water vapour contents – different O
2
contents
in the flue gas, but also to a different combustion temperature. Through constant measuring of the internal resistance of
the measuring element, the above-mentioned factors can be compensated mathematically and result in precise results in
the working range of (80 - 500Ω) independent of the impacting factors.
Rectification: Call service technician – possible causes:
1. First, clean the O
2
sensor carrier (do not remove) and the O
2
sensor with a brass brush. Then place the sensor vertically
and gently tap it onto the sensor (accumulated dust in the sensor body is removed through the bore in the cone point).
Then remove the remaining dust by blowing air through the four bores. Too much dust can reduce the operating
temperature. Afterwards, run an O
2
calibration. If the error occurs again, continue with step 2.
2. The heating element in the O
2
sensor is used up.
3. Replace O
2
sensor and calibrate afterwards. Check the note in chapter 4.4.1 for manual calibration of the O
2
sensor.
Controller function: The controller continues working with the O
2
-control program, but with reduced O
2
-measuring accuracy.
Note: If the used up O
2
sensor is used for another combustion, an error message appears after approx. 1 hour. The boiler and
chimney may be fouled.
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