Suzuki 2000 Grand Vitara SQ625 Service Manual page 71

TROUBLESHOOTING (DTC P0171/P0172)
STEP
1 Was "ENGINE DIAG. FLOW TABLE" performed?
2 Is there DTC(s) other than "DTC P0171/P0172"?
3 Check intake system and exhaust system for leakage.
Are intake system and exhaust system in good
condition?
4 Check fuel pressure referring to TABLE B-3 in this
section.
Is check result satisfactory?
5 Check fuel injectors referring to "FUEL INJECTOR
INSPECTION" in "ENGINE AND EMISSION CONTROL
SYSTEM" section.
Is check result satisfactory?
6 Check fuel level sensor referring to DTC P0461 Diag.
Flow Table.
Is check result satisfactory?
7 Check MAF sensor for performance referring to DTC
P0101 Diag. Flow Table.
Is check result satisfactory?
8 Check ECT sensor referring to "ENGINE AND
EMISSION CONTROL SYSTEM" section.
Is check result satisfactory?
9 Check HO2S-1 referring to DTC P0131/P0132 Diag.
Flow Table.
Is check result satisfactory?
ACTION
ENGINE DIAGNOSIS (G16 / J20 ENGINES) 6-67
YES
Go to Step 2.
Go to applicable
DTC FLOW
TABLE.
Go to Step 4.
Go to Step 5.
Go to Step 6.
Go to Step 7.
Go to Step 8.
Go to Step 9.
Substitute a known-
good ECM (PCM)
and recheck.
NO
Go to "ENGINE
DIAG. FLOW DIAG FLOW
TABLE".
Go to Step 3.
Repair or replace.
Repair or replace.
Faulty injector(s).
Faulty fuel level
sensor or its circuit.
Faulty MAF sensor
or its circuit.
Faulty ECT sensor.
Faulty HO2S-1.