DTC Troubleshooting

WARNING: This page is about a different car, the 2007 Suzuki SX4. However, it is still accessible from the selected car via links, so may be relevant.

DTC TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Was "Engine and Emission Control System Check" performed?	Go to Step 2.	Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2	DTC check Is there DTC(s) other than P0139?	Go to applicable DTC(s).	Go to Step 3.
3	Exhaust system for leakage check Check exhaust system for leakage. Is it in good condition?	Go to Step 4.	Repair or replace defective parts.
4	HO2S circuit check Disconnect connector from HO2S and ECM with ignition switch turned OFF. Check for proper terminal connection to HO2S connector and ECM connector. If connections are OK, check that HO2S circuit is as follows. Wiring harness resistance of each "Signal circuit of HO2S", "Ground circuit of HO2S" and "Control circuit of HO2S heater" is less than 1 Ω. Insulation resistance between "Signal circuit of HO2S" and vehicle body ground is infinity. Insulation resistance of wire harness is infinity between "Signal circuit of HO2S" terminal and each other terminal at HO2S connector. Circuit voltage between "Signal circuit of HO2S" and vehicle body ground is 0 V with ignition switch turned ON. Is it in good condition?	Replace HO2S and recheck. If this DTC is detected again, substitute a known-good ECM.	Repair or replace defective wiring harness / connector.