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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 117 (Engine Controls - Self-Diagnostics - 3.0L) >> Diagnostic Tests >> DTC P0056: Ho2S Heater Circuit - Bank 2, Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off for 10 seconds. Start engine. Using scan tool, monitor status of DTC. If this DTC ran and failed LAST TEST, go to next step. If this DTC did not fail LAST TEST, problem is intermittent. See DIAGNOSTIC AIDS  .
  2. Turn ignition on, engine off. Check EMISS fuse (10-amp) located in underhood fuse block. Replace as necessary. Disconnect HO2S bank 2 sensor 2 harness connector. HO2S bank 2 sensor 2 is located directly behind pre-converter for cylinders No. 2, 4 and 6. Connect a test light between HO2S harness connector terminals No. 1 (White wire) and No. 2 (Yellow wire). Start engine. If test light illuminates and turns off at least once every 10 seconds, go to next step. If test light does not illuminates and turns off at least once every 10 seconds, go to step  4 .
  3. Turn ignition on, engine off. Using a DVOM, measure voltage between ground and HO2S harness connector terminal No. 2 (Yellow wire). If voltage reading is 2.6-4.6 volts, check connectors. Repair as necessary. If connectors are okay, replace HO2S bank 2 sensor 2. If voltage reading is not 2.6-4.6 volts, replace ECM.
  4. Connect test light between ground and HO2S harness connector terminal No. 1 (White wire). If test light does not illuminate, repair open in White wire between HO2S and underhood fuse block. If test light illuminates, check for open in Yellow wire between HO2S and ECM. Repair as necessary. If circuit is okay, check connectors. Repair as necessary. If connectors are okay, replace ECM.
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