Test Procedure
- DW1 CHECK FOR DTCS
Are DTCs P0036, P0037, P0038, P0041, P0054, P0056, P0060, P00D2, P0136, P0137, P0138, P0139, P013A, P013B, P013C, P013E, P0140, P0141, P014A, P0157, P0158, P0159, P0161, P2A01 or P2A04 present?
Yes No GO to DW2 . RETURN to NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX for further direction. - DW2 VISUALLY INSPECT THE HO2S HARNESS
- Ignition OFF.
- Verify the HO2S connectors are connected to the correct engine bank.
- Visually inspect for:
- crossed sensor wires
- pinched, shorted, and corroded wiring and pins
- oil or water contamination
- damaged HO2S
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.For DTCs P0036, P0037, P0038, P0054, P0056, P0060, P0141 or P0161, GO to DW13.
For DTC P0041, GO to DW3 .
For all others, GO to DW5. - DW3 CARRY OUT THE KOER SELF-TEST
- Engine at normal operating temperature.
- Carry out the PCM KOER self-test.
Is DTC P0041 present?
Yes No GO to DW7. GO to DW4 . - DW4 CHECK FOR A SOURCE OF POTENTIAL HO2S CONTAMINATION
- Investigate the following items as potential sources of HO2S contamination:
- use of unapproved silicon sealers
- fuel contaminated by silicon additives
- excessive oil consumption
- glycol leaking internally in the engine
- contaminated fuel
- short drive cycles in cold weather
- use of unapproved cleaning agents
Is a concern present?
Yes No REPAIR the source of the contamination.
CHANGE the engine oil and oil filter.
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test.For DTCs P013A or P013C, GO to DW6.
For all others, GO to DW5 . - Investigate the following items as potential sources of HO2S contamination:
- DW5 CHECK FOR UNMETERED AIR LEAKS NOTE: Fuel calculations can be affected by unmetered air leaks.
- Carefully inspect the following areas for potential air leaks:
- hoses connecting to the mass air flow (MAF) sensor assembly
- hoses connecting to the throttle body
- intake manifold gasket leaks
- positive crankcase ventilation (PCV) system
- the vacuum lines are disconnected
- incorrectly seated engine oil dipstick, tube or oil fill cap
Are any air leaks present?
Yes No REPAIR the source of the air leak. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test.GO to DW6 . - Carefully inspect the following areas for potential air leaks:
- DW6 CHECK FOR EXHAUST SYSTEM CONCERNS
- Inspect the exhaust system for the following:
- exhaust leaks at flanges and gaskets
- exhaust leaks at the HO2S
- aftermarket accessories and performance modifications
Is a concern present?
Yes No For DTCs P013A or P013C, REPAIR as necessary. CARRY OUT the HO2S and Catalyst OBD Monitor Drive Cycle Procedures. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .
Clear the PCM DTCs. REPEAT the self-test.
For all others, REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.For DTCs P013A or P013C, INSTALL a new HO2S. REFER to the appropriate Electronic Engine Controls article. CARRY OUT the HO2S and Catalyst OBD Monitor Drive Cycle Procedures. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .
Clear the PCM DTCs. REPEAT the self-test.
For all others, GO to DW7 . - Inspect the exhaust system for the following:
- DW7 CHECK FOR FUEL SELECTION CONCERNS
- Verify with the customer that flex fuel is not being used on a non-flex fuel vehicle.
Is a concern present?
Yes No REPAIR as necessary. Clear the PCM DTCs. REPEAT the self-test. GO to DW8 . - DW8 CHECK THE HO2S SIGNAL NOTE: Diagnose the suspect sensor indicated by the DTC.NOTE: Verify the harness pins are in the correct location.NOTE: HO2S is displayed as O2S on the scan tool.
- Ignition OFF.
- For HO2S12,
- HO2S12 connector disconnected.
- Ignition ON, engine running.
- Access the PCM and monitor the O2S12 (VOLT) PID.
- For HO2S22,
- HO2S22 connector disconnected.
- Ignition ON, engine running.
- Access the PCM and monitor the O2S22 (VOLT) PID.
Is the voltage less than 1.1 V?
Yes No GO to DW9 . GO to DW10. - DW9 CHECK THE HO2S CIRCUIT CONTINUITY
- Ignition OFF.
- For HO2S12,
- Connect a 5 amp fused jumper wire between the following:
Point A HO2S12 Connector, Harness Side Point B HO2S12 Connector, Harness Side HO2S12 VPWR - Ignition ON, engine running.
- Access the PCM and monitor the O2S12 (VOLT) PID.
- For HO2S22,
- Connect a 5 amp fused jumper wire between the following:
Point A HO2S22 Connector, Harness Side Point B HO2S22 Connector, Harness Side HO2S22 VPWR - Ignition ON, engine running.
- Access the PCM and monitor the O2S22 (VOLT) PID.
Is the voltage greater than 1 V?
Yes No INSTALL a new HO2S. REFER to the appropriate Electronic Engine Controls article.
Clear the PCM DTCs. REPEAT the self-test.GO to DW10 . - DW10 CHECK THE HO2S CIRCUITS FOR AN OPEN
- Ignition OFF.
- Remove the jumper wires, if connected.
- Check the connector (both halves) for any water contamination.
- PCM connector disconnected.
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) PCM Connector, Harness Side HO2S12 HO2S12 SIGRTN SIGRTN - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) PCM Connector, Harness Side HO2S22 HO2S22 SIGRTN SIGRTN
Are the resistances less than 5 ohms?
Yes No GO to DW11 . REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DW11 CHECK THE HO2S CIRCUIT FOR A SHORT
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) HO2S12 Connector, Harness Side HO2S12 SIGRTN HO2S12 VPWR - Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) HO2S12 Ground - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) HO2S22 Connector, Harness Side HO2S22 SIGRTN HO2S22 VPWR - Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) HO2S22 Ground
Are the resistances greater than 10K ohms?
Yes No GO to DW12 . REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - DW12 CHECK THE HO2S CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- For HO2S12,
- Measure the voltage between:
(+) HO2S12 Connector, Harness Side (-) HO2S12 Ground - For HO2S22,
- Measure the voltage between:
(+) HO2S22 Connector, Harness Side (-) HO2S22 Ground
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. GO to DW13 . - DW13 CARRY OUT A THOROUGH WIGGLE TEST ON THE HO2S HARNESS
- Ignition OFF
- PCM connector connected
- For HO2S12
- HO2S12 connector connected
- Ignition ON, engine OFF
- Access the PCM and monitor the O2S12 (VOLT) PID
- Carry out a thorough wiggle test on the HO2S12 harness
- For HO2S22,
- HO2S22 connector connected
- Ignition ON, engine OFF
- Access the PCM and monitor the O2S22 (VOLT) PID
- Carry out a thorough wiggle test on the HO2S22 harness
Does the voltage change during the wiggle test?
Yes No REPAIR as necessary. Clear the PCM DTCs. REPEAT the self-test. For DTC P00D2, Go to DW14 . For all others, Go to DW19 . - DW14 CHECK FOR VPWR NOTE: Diagnose the suspect sensor indicated by the DTC.
- Ignition OFF.
- For HO2S12,
- HO2S12 connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) HO2S12 Connector, Harness Side (-) VPWR Ground - For HO2S22,
- HO2S22 connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) HO2S22 Connector, Harness Side (-) VPWR Ground
Is the voltage greater than 10.5 V?
Yes No GO to DW15 . REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DW15 CHECK THE HO2S HEATER CIRCUIT FOR AN OPEN
- Ignition OFF.
- PCM connector disconnected.
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) PCM Connector, Harness Side HTR12 HTR12 - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) PCM Connector, Harness Side HTR22 HTR22
Is the resistance less than 5 ohms?
Yes No GO to DW16 . REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DW16 CHECK THE HO2S HEATER FOR SHORT CIRCUITS
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) HTR12 Ground - Measure the resistance between:
(+) HO2S12 Connector, Harness Side (-) HO2S12 Connector, Harness Side HTR12 VPWR HTR12 SIGRTN HTR12 HO2S12 - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) HTR22 Ground - Measure the resistance between:
(+) HO2S22 Connector, Harness Side (-) HO2S22 Connector, Harness Side HTR22 VPWR HTR22 SIGRTN HTR22 HO2S22
Are the resistances greater than 10K ohms?
Yes No GO to DW17 . REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - DW17 CHECK THE INTERNAL RESISTANCE OF THE HO2S HEATER
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Component Side (-) HO2S12 Connector, Component Side HTR12 VPWR - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Component Side (-) HO2S22 Connector, Component Side HTR22 VPWR
Is the resistance between 2 - 30 ohms?
Yes No GO to DW18 . INSTALL a new HO2S. REFER to the appropriate Electronic Engine Controls article. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test. - DW18 CHECK THE HEATER CIRCUIT FOR AN INTERNAL SHORT TO GROUND
- For HO2S12,
- Measure the resistance between:
(+) HO2S12 Connector, Component Side (-) HO2S12 Connector, Component Side HTR12 SIGRTN - Measure the resistance between:
(+) HO2S12 Connector, Component Side (-) HTR12 Ground - For HO2S22,
- Measure the resistance between:
(+) HO2S22 Connector, Component Side (-) HO2S22 Connector, Component Side HTR22 SIGRTN - Measure the resistance between:
(+) HO2S22 Connector, Component Side (-) HTR22 Ground
Is the resistance greater than 10K ohms?
Yes No GO to DW19 . INSTALL a new HO2S. REFER to the appropriate Electronic Engine Controls article.
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test. - DW19 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins
- corrosion
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test.
- Verify the concern is still present.
Is the concern still present?
Yes No INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) , Programming the VID Block for a Replacement PCM. The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.