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Home >> Geo >> 1996 >> Metro Base, 2D Hatchback, 1.0 6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0136 - Ho2S2 Circuit >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to DLC. Start engine and run at 2000 RPM for 5 minutes. Select HO2S2 parameter on scan tool. Observe HO2S2 voltage. If HO2S2 voltage is less than 1275 mV, go to next step. If voltage is not as specified, go to step 3).
  2. Turn ignition on. Select CLEAR INFORMATION function. Operate vehicle within FREEZE FRAME conditions. If DTC P0136 resets, go to next step. If DTC P0136 does not reset, check for an intermittent problem. See TESTS W/O CODES article.
  3. Turn ignition on. Disconnect HO2S2 connector. Using a voltmeter, measure voltage between ground and HO2S2 sensor signal circuit (Yellow wire) at harness connector. If reading is 4-5 volts, go to next step. If reading is not as specified, check for poor connection, open, or short in Yellow wire between HO2S2 and PCM connectors. Repair as necessary. If wire is okay, replace PCM. Retest system.
  4. Observe HO2S2 parameter on scan tool. Connect a fused jumper wire between PCM side of HO2S2 signal circuit (Yellow wire) and ground. If scan tool indicates HO2S2 voltage less than 100 mV, go to next step. If reading is not as specified, replace PCM. Retest system.
  5. Using a test light connected to battery positive, probe HO2S2 ground circuit (Light Green/Black wire). If test light comes on, replace HO2S2. If test light does not come on, check for poor connection or open in Light Green/Black wire. Repair as necessary. If wire is okay, replace PCM. Retest system.
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