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Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
NOTE: Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
  1. If engine system check has been performed, go to next step. If engine system check has not been performed, perform TEST D: ENGINE SYSTEM CHECK  under SYSTEM TESTS, then go to next step.
  2. Turn ignition switch to LOCK position. Disconnect HO2S-2 4-pin harness connector C50, located after front catalytic converter. See Figure. Check HO2S-2 and harness connector terminals for corrosion or poor connection. If connector terminals are faulty, repair as necessary and repeat DTC CONFIRMATION TEST . If connector terminals are okay, turn ignition switch to ON position and measure voltage between ground and HO2S-2 harness connector C50 terminal No. 4 (Black/White wire). See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit in Black/White wire between HO2S-2 and fuse/relay box. After repair, repeat DTC CONFIRMATION TEST .
  3. Turn ignition switch to LOCK position. Disconnect ECM harness connector C46. See Figure. Measure resistance between ECM harness connector C46 terminal No. 7 and HO2S-2 harness connector C50 terminal No. 4 (Black/White wire). See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or short circuit in Black/White wire between HO2S-2 and ECM. After repair, repeat DTC CONFIRMATION TEST .
  4. Measure resistance between ground and HO2S-2 harness connector C50 terminal No. 3 (Pink/Blue wire). See Figure.If resistance is infinity, go to next step. If any resistance is found, repair short to ground in Pink/Blue wire between HO2S-2 and ECM. After repair, repeat DTC CONFIRMATION TEST .
  5. Turn ignition switch to ON position. Measure voltage between ground and HO2S-2 harness connector C50 terminal No. 3 (Pink/Blue wire). See Figure.If voltage is zero volts, go to next step. If any voltage is found, repair short to voltage in Pink/Blue wire between HO2S-2 and ECM. After repair, repeat DTC CONFIRMATION TEST .
  6. Turn ignition switch to LOCK position. Reconnect HO2S-2 harness connector. Disconnect ECM harness connector C45. See Figure. Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector C45 terminal No. 6 (Pink/Blue wire). See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit in Pink/Blue wire between HO2S-2 and ECM. After repair, repeat DTC CONFIRMATION TEST .
  7. Turn ignition switch to LOCK position. Disconnect HO2S-2 harness connector. Measure resistance between HO2S-2 harness connector terminals No. 3 and 4 (component side). See Figure. If resistance is 5-7 ohms at 77°F (25°C), go to next step. If resistance is not 5-7 ohms at 77°F (25°C), replace HO2S-2. See HEATED OXYGEN SENSORS NO. 1 & 2 under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST .
  8. Reconnect HO2S-2 harness connector. Measure resistance between ECM harness connectors C46 terminal No. 7 (Black/White wire) and C45 terminal No. 6 (Pink/Blue wire). See Figure. If resistance is less than 15 ohms, HO2S-2 heater circuit is okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST . If resistance is 15 ohms or more, repair short circuit in Black/White wire and/or Pink/Blue wire between HO2S-2 and ECM. After repair, repeat DTC CONFIRMATION TEST .
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