Suzuki SY413 Service Manual page 2666

DTC P0171 FUEL SYSTEM TOO LEAN
DTC P0172 FUEL SYSTEM TOO RICH
CIRCUIT DESCRIPTION
Ignition
switch
Relay box
Main
fuse
DTC DETECTING CONDITION
D When following condition occurs while engine running under
closed loop condition.
– Air/ fuel ratio too lean
Total fuel trim (short and long terms added) is
more than 30%
or
– Air/ fuel ratio too rich
(Total fuel trim is less than – 30%)
: 2 driving cycle detection logic, continuous monitoring.
ENGINE GENERAL INFORMATION AND DIAGNOSIS (G13/G16 ENGINE WITH WU TWC) 6-1-67
Main relay
No.1 injector
No.2 injector
No.3 injector
No.4 injector
To ignition
switch
To other sensor
POSSIBLE CAUSE
D Vacuum leaks (air drawn in).
D Exhaust gas leakage.
D Heated oxygen sensor-1 circuit malfunc-
tion.
D Fuel pressure out of specification.
D Fuel injector malfunction (clogged or
leakage).
D MAP sensor poor performance.
D ECT sensor poor performance.
D IAT sensor poor performance.
D TP sensor poor performance.
D EVAP control system malfunction.
D PCV valve malfunction.
ECM
(PCM)