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Home >> Pontiac >> 2002 >> Aztek FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0130: Ho2S Sensor 1 Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Allow the engine to idle at operating temperature. Observe the HO2S 1 voltage parameter with a scan tool. Clear the DTC and record the Freeze/Frame Failure Records data if the HO2S 1 voltage is fixed at bias voltage. Does the HO2S 1 voltage fluctuate rapidly above and below 350-550 mV? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn OFF the ignition. Disconnect the HO2S 1 connector. Turn ON the ignition, with the engine OFF. Measure the voltage from the high signal circuit of the HO2S 1 harness connector, on the engine side, to a good ground with a Digital Multimeter (DMM). Is the HO2S voltage 0.425-0.500 V? If yes, go to next step. If no, go to step  6.
  5. Turn OFF the ignition. Connect a 3-amp fused jumper wire between the HO2S 1 high signal circuit, and the HO2S 1 low signal circuit. Turn ON the ignition, with the engine OFF. Observe the HO2S 1 voltage on the scan tool. Does the scan tool display less than 25 mV? If yes, go to step  8. If no, go to next step.
  6. Turn OFF the ignition. Disconnect both PCM connectors. Measure the resistance of each of the following circuits with a DMM:
    • HO2S 1 high signal circuit between HO2S connector and the PCM connector.
    • HO2S 1 low signal circuit between HO2S connector and the PCM connector.
    • HO2S 1 low reference circuit between pin C1-29 and pin C2- 80 of the PCM connectors.

    Is the resistance of each circuit less than 5 ohms? If yes, go to step  11. If no, go to next step.

  7. Repair the circuit that measured a high resistance or an open. After repairs, go to step  14.
  8. Remove the jumpers from the HO2S 1 terminals. Connect a test lamp between the HO2S 1 ignition voltage circuit and the HO2S 1 heater low control circuit terminals, on the engine harness side. Start the engine. Does the test lamp illuminate? If yes, go to next step. If no, see DTC P0135: HO2S HEATER CIRCUIT - SENSOR 1 .
  9. Inspect for the following conditions that may affect the HO2S operation:
      NOTE: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.
    • HO2S for contamination.
      • NOTE: Do not remove this pigtail from either the Heated Oxygen Sensor (HO2S) or the oxygen sensor (O2S). Removing the pigtail or the connector will affect sensor operation. Handle the oxygen sensor carefully. Do not drop the HO2S. Keep the in-line electrical connector and the louvered end free of grease, dirt, or other contaminants. Do not use cleaning solvents of any type. Do not repair the wiring, connector or terminals. Replace the oxygen sensor if the pigtail wiring, connector, or terminal is damaged. This external clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors, or terminals could result in the obstruction of the air reference and degraded sensor performance. The following guidelines should be used when servicing the heated oxygen sensor: Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Do not damage the sensor pigtail and harness wires in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. Ensure the sensor or vehicle lead wires are not bent sharply or kinked. Sharp bends or kinks could block the reference air path through the lead wire. Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will cause poor engine performance. Ensure that the peripheral seal remains intact on the vehicle harness connector in order to prevent damage due to water intrusion. The engine harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed.
    • Chafed, burnt, cut, pinched, or otherwise damaged HO2S wiring.
    • The HO2S must have a clean air reference in order to function properly. This clean air reference is obtained by way of the HO2S wires. Obstruction of the air reference and degraded HO2S performance could result from any attempt to repair the above conditions.
    • Exhaust system leaks or restrictions.
    • Evaporative (EVAP) emissions canister purge. Inspect the EVAP control system.
    • The fuel pressure. Incorrect fuel pressure can affect HO2S operation.

    Did you find and correct the condition? If yes, go to step  14. If no, go to next step.

  10. Inspect for poor connections at the HO2S 1 connector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Inspect for poor connections at the PCM harness connectors. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the HO2S 1 sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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