Operation Section
-91-
Table a. MI-04 Diagnostic Fault Codes (Flash Codes)
DFC
Probable Fault
Action
Corrective Action, First Check
72 AFRTrimValveLowerDC
FTV duty cycle at lower (lean) limit
(G643E only)
Stored Fault Code
(MIL, Disable Adaptive
learns)
Engine measured Air/Fuel ratio at the
O2 sensor is excessively lean.
If LP fuel in LP tank is not enough, this
fault code can be set. If LP tank is
frozen, this fault code can be set, too.
It is not system trouble.
z
Check for intake manifold leaks
z
Check balance line (vacuum hose)
connection at the regulator
z
Check N-CA55-500-TR mixer for
heavy end build-up and operation
(see mixer section)
z
Check N2001 secondary for
operation or low primary pressure
(see N2001 Regulator section)
73 AFRTrimValveUpperDC
FTV duty cycle at high (rich) limit
(Expected fault when FTV
connector is unplugged)
(G643E only)
Stored Fault Code
(MIL, Disable Adaptive
learns)
Engine measured Air/Fuel ratio at the
O2 sensor is excessively rich
Check FTV connector wiring for an
open circuit
z
Check N-CA55-500-TR mixer for
heavy end build-up and operation
(see mixer section)
z
Check N2001 secondary for
operation (see N2001 Regulator
section)
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