Dtc P0171 Fuel System Too Lean; Dtc P0172 Fuel System Too Rich - Suzuki Ignis Service Manual

6-76 ENGINE GENERAL INFORMATION AND DIAGNOSIS

DTC P0171 FUEL SYSTEM TOO LEAN

DTC P0172 FUEL SYSTEM TOO RICH

WIRING DIAGRAM / CIRCUIT DESCRIPTION
2
3
1. Injector
2. HO2S-1
3. WU-TWC (Warm up-three way catalytic convec-
tor)
4. Sensed information
5. ECM
DTC DETECTING CONDITION
When one of the following conditions 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%)
• Air/fuel ratio too rich
(Total fuel trim is less than – 30%)
✱2 driving cycle detection logic, continuous monitoring.
4
5
1
2
[a] : Signal to decrease amount of fuel injection
[b] : Signal to increase amount of fuel injection
[c] : High voltage
[d] : Low voltage
[e] : A/F mixture becomes richer
[a]
[b]
1
[e]
[f]
+B
1
BLU/YEL
BLU/WHT
BLU/RED
BLU/ORN
BLK/ORN
BLK/ORN
WHT
ORN
E11
POSSIBLE CAUSE
• Vacuum leaks (air drawn in).
• Exhaust gas leakage.
• Heated oxygen sensor-1 circuit malfunction.
• Fuel pressure out of specification.
• Fuel injector malfunction (clogged or leakage).
• MAP sensor poor performance.
• ECT sensor poor performance.
• IAT sensor poor performance.
• TP sensor poor performance.
• EVAP control system malfunction.
• PCV valve malfunction.
[c]
5 [d]
2
[g]
[h]
ECM
C42-9
C42-21
C42-31
C42-8
C42-1
C42-3
C42-13
C42-10
[f] : A/F mixture becomes leaner
[g] : Oxygen concentration decreases
[h] : Oxygen concentration increases