Suzuki GA413 Service Manual page 839

DTC P0171 FUEL SYSTEM TOO LEAN
DTC P0172 FUEL SYSTEM TOO RICH
CIRCUIT DESCRIPTION
[a]: Signal to decrease amount of fuel injection
[b]: Signal to increase amount of fuel injection
[c]: A/F mixture becomes leaner
(Oxygen concentration increases)
[d]: A/F mixture becomes richer
(Oxygen concentration decreases)
[e]: High voltage
[f]: Low voltage
1. Injector
2. Heated oxygen sensor-1 (HO2S-1)
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 6-63
POSSIBLE CAUSE
D Vacuum leaks (air drawn in).
D Exhaust gas leakage.
D Heated oxygen sensor-1 circuit
malfunction.
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.