Siemens LMV5 Series Technical Instructions page 263

Error Diag.
Device Display
Code Code
Any # -
Below O2 Min
01
Value
O2 Min Values
02
undefined
O2 Setpoints
03
B5 LMV5..
undefined
O2 Delay Time
04
undefined
Actual O2 Value
05
invalid
O2 Value
06 Prepurging
not reached
Section 7
Meaning for the LMV5x System
Fault with Base Unit (LMV5) or Oxygen Sensor (QGO2..)
O2 monitor
O2 value has dropped below O2 min. value
Invalid O2 min. value
Invalid O2 setpoint
Invalid O2 delay time
No valid actual O2 value in operation for ≥ 3 s
During prepurging, the parameterized air
oxygen content of +/- 2 % was not reached
1) If fault occurs sporadically, reduce electrical noise.
2) If fault occurs continuously, replace LMV5.
1) Check the %O2 between the O2 guard curve and the
O2 setpoint curve. Increase the %O2 "gap" between
these two curves at the load point where the fault is
occurring.
2) Check for mechanical lash (slop) between actuators
and dampers / valves. Also check dampers for worn
bearings. Change to zero lash flexible couplings if
necessary.
3) If necessary, adjust parameters O2ModOffset and /
or O2CtrlThreshold
Set a point for the O2 min value curve (or O2 guard
curve) for each point set up on the ratio control curve
(12 points on ratio control curve = 12 points on O2 min
value curve)
Set a point for the O2 setpoint curve (or O2 Control
Curve) for each point set up on the ratio control curve
except for point 1 (12 points on ratio control = 11 points
on O2 setpoint curve)
The delay time has not been measured successfully at
Point 2 or the highest curve point. See O2 trim section
for possible causes.
1) Check the wiring between the O2 Module and the O2
sensor.
2) Check the power supply to the O2 Module
1) Check the parameter O2 Content Air . This %O2
must be reached within +/- 2% during prepurge.
2) Check prepurge time. The time that is set may not
be long enough to completely purge the boiler.
3) Sensor may be dirty. Do not blow out with
compressed air when hot! Cool, then blow out with low
pressure compressed air (less than 15 psi).
4) O2 Sensor may have reached the end of its service
life (check resistance through AZL - QGO Resistance )
If greater than 140 -150 ohms, replace sensor.
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Corrective Action
SCC Inc.