Test Procedure
- DZ1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS)
Are DTCs P0030, P0040, P0050, P0053, P0059, P0130, P0131, P0132, P0133, P0134, P0135, P0150, P0151, P0152, P0153, P0154, P0155, P1127, P164A, P164B, P2096, P2097, P2098, P2099, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2627, P2628, P2629, P2630, or P2631 present?
Yes No For DTC P0040, GO to DZ6.
For DTCs P0133 or P0153, GO to DZ18.
For DTC P1127, GO to DZ22.
For DTCs P2096, P2097, P2098 or P2099, GO to DZ24.
For DTCs P164A, P164B, P2626, P2627, P2628, P2629, P2630 or P2631, GO to DZ27.
For all others, GO to DZ2.For symptoms without DTCs, GO to DZ27.
For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . - DZ2 VISUALLY INSPECT THE UO2S HARNESS
- Ignition OFF.
- Visually inspect for:
- pinched, shorted, and corroded wiring and pins
- oil or water contamination
- crossed sensor wires
- damaged UO2S sensor
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.For DTCs P0030 or P0050, GO to DZ3.
For DTCs P0053, P0059, P0135 or P0155, GO to DZ7.
For DTCs P0130, P0131, P0132, P0150, P0151, P0152, P2243, P2247, P2251 or P2254, GO to DZ12.
For all others, GO to DZ21. - DZ3 CHECK FOR MISFIRE CONCERNS AND AFTERMARKET EQUIPMENT
- Ignition OFF.
- Check for the following:
- misfire concern
- non-factory or aftermarket equipment that may increase the exhaust temperature
- Universal HO2S-Front connector disconnected.
- Check the universal HO2S connector for damage or corrosion.
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.GO to DZ4. - DZ4 CHECK THE UO2SHTR CIRCUIT FOR A SHORT TO VOLTAGE
- PCM connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2SHTR Ground
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. GO to DZ5. - DZ5 CHECK THE UO2S, UO2SGREF, UO2SHTR CIRCUITS FOR AN OPEN IN THE HARNESS
- Ignition OFF.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) PCM Connector, Harness Side UO2S UO2S UO2SGREF UO2SGREF UO2SHTR UO2SHTR
Are the resistances less than 5 ohms?
Yes No GO to DZ10. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DZ6 CROSSED SENSOR WIRES
- Ignition OFF.
- Check the vehicle repair history.
- Verify the connectors are connected to the correct engine bank.
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.Unable to duplicate or identify the concern at this time.
GO to PINPOINT TEST Z . - DZ7 DTCS P0053, P0059, P0135 AND P0155: CHECK FOR VPWR IN THE HARNESS
- Ignition OFF.
- Universal HO2S-Front connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) VPWR Ground
Is the voltage greater than 10 V?
Yes No GO to DZ8. REPAIR the open circuit. CHECK the fuses.
Clear the PCM DTCs. REPEAT the self-test. - DZ8 CHECK THE UO2SHTR CIRCUIT FOR AN OPEN IN THE HARNESS
- Ignition OFF.
- Universal HO2S-Front connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) PCM Connector, Harness Side UO2SHTR UO2SHTR
Is the resistance less than 5 ohms?
Yes No GO to DZ9. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DZ9 CHECK THE UO2SHTR CIRCUIT FOR A SHORT IN THE HARNESS
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) Vehicle Battery UO2SHTR Negative terminal - Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) Universal HO2S-Front Connector, Harness Side UO2SHTR UO2S UO2SHTR UO2SGREF UO2SHTR UO2SPC UO2SHTR UO2SPCT UO2SHTR VPWR
Are the resistances greater than 10K ohms?
Yes No GO to DZ10. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- DZ10 CHECK THE INTERNAL RESISTANCE OF THE UNIVERSAL HO2S HEATER
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Component Side (-) Universal HO2S-Front Connector, Component Side VPWR UO2SHTR
Is the resistance between 1.8 - 6 ohms?
Yes No GO to DZ11. INSTALL a new Universal 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. - Measure the resistance between:
- DZ11 CHECK THE UO2SHTR CIRCUIT FOR AN INTERNAL SHORT TO GROUND
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Component Side (-) UO2SHTR Ground
Is the resistance greater than 10K ohms?
Yes No GO to DZ32. INSTALL a new Universal 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. - Measure the resistance between:
- DZ12 CHECK THE UO2S AND UO2SGREF CIRCUITS FOR AN OPEN IN THE HARNESS
- Ignition OFF.
- Universal HO2S-Front connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) PCM Connector, Harness Side UO2S UO2S UO2SGREF UO2SGREF
Are the resistances less than 5 ohms?
Yes No GO to DZ13. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DZ13 CHECK THE UO2S, UO2SGREF, UO2SPC, AND UO2SPCT CIRCUITS FOR A SHORT TO GROUND IN THE HARNESS
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2S Ground UO2SGREF Ground UO2SPC Ground UO2SPCT Ground
Are the resistances greater than 10K ohms?
Yes No GO to DZ14. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- DZ14 CHECK THE UO2S, UO2SGREF, UO2SPC, AND UO2SPCT CIRCUITS FOR A SHORT TO VOLTAGE IN THE HARNESS
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2S Ground UO2SGREF Ground UO2SPC Ground UO2SPCT Ground
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. For F-150 5.0L, F-150 6.2L, F-Series Super Duty, Mustang 5.0L, and Mustang 5.4L, GO to DZ15.
For Edge, Escape/Mariner, Explorer, F-150 3.7L, Fusion 2.5L, Fusion 3.0L, Milan, MKX and Mustang 3.7L, GO to DZ16.
For all others, GO to DZ17. - DZ15 F-150 5.0L, F-150 6.2L, F-SERIES SUPER DUTY, MUSTANG 5.0L, OR MUSTANG 5.4L: CHECK THE UO2SGREF CIRCUIT FOR VOLTAGE
- Ignition OFF.
- PCM connector connected.
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2SGREF Ground
Is the voltage between 2 - 2.4 V?
Yes No INSTALL a new Universal 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.GO to DZ32. - DZ16 EDGE, ESCAPE/MARINER, EXPLORER, F-150 3.7L, FUSION 2.5L, FUSION 3.0L, MILAN, MKX OR MUSTANG 3.7L: CHECK THE UO2SGREF CIRCUIT FOR VOLTAGE
- Ignition OFF.
- PCM connector connected.
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2SGREF Ground
Is the voltage between 3.5 - 3.7 V?
Yes No INSTALL a new Universal 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.GO to DZ32. - DZ17 ALL OTHERS: CHECK THE UO2SGREF CIRCUIT FOR VOLTAGE
- Ignition OFF.
- PCM connector connected.
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2SGREF Ground
Is the voltage between 2.4 - 2.6 V?
Yes No INSTALL a new Universal 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.GO to DZ32. - DZ18 CARRY OUT THE KOER SELF-TEST
- Engine at normal operating temperature.
- Carry out the PCM self-test.
Are any DTCs present other than P0133 or P0153?
Yes No DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to DZ19. - DZ19 CHECK FOR A SOURCE OF POTENTIAL CONTAMINATION
- Investigate the following items as potential sources of universal HO2S contamination:
- use of unapproved silicon sealers
- fuel contaminated by silicon additives
- excessive oil consumption
- glycol leaking internally in the engine
- lead-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.GO to DZ20. - Investigate the following items as potential sources of universal HO2S contamination:
- DZ20 CHECK THE UNIVERSAL HO2S RESPONSE TEST RESULTS
- Ignition ON, engine OFF.
- Access the diagnostic monitoring test results for the HO2S11 and HO2S21. Refer to DIAGNOSTIC MONITORING TEST RESULTS MODE 6 .
Is the indicated value greater than the minimum threshold?
Yes No Unable to duplicate or identify the concern at this time.
Clear the PCM DTCs. REPEAT the self-test.INSTALL a new Universal 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. - DZ21 CHECK THE UO2SPC CIRCUIT FOR AN OPEN IN THE HARNESS
- Ignition OFF.
- Universal HO2S-Front connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) PCM Connector, Harness Side UO2SPC UO2SPC
Is the resistance less than 5 ohms?
Yes No INSTALL a new Universal HO2S. REFER to the appropriate Electronic Engine Controls article. .
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DZ22 EXHAUST TEMPERATURE OUT OF RANGE NOTE: Diagnose all other powertrain related DTCs first.
- Ignition ON, engine running.
- Engine at normal operating temperature.
- Access the PCM and monitor the HTR11 (MODE) and HTR21 (MODE) PIDs.
Are the PID states ON?
Yes No CARRY OUT the KOER self-test. RUN the engine until the PID indicates ON.
CARRY OUT the KOER self-test. - DZ23 CARRY OUT THE KOER SELF-TEST
- Engine at normal operating temperature.
- Carry out the PCM KOER self-test.
Are any DTCs present other than P2096, P2097, P2098, P2099?
Yes No DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to DZ24. - DZ24 VISUALLY INSPECT THE UPSTREAM AND DOWNSTREAM HO2S CONNECTORS
- Ignition OFF.
- HO2S connector disconnected.
- Universal HO2S-Front connector disconnected.
- Check for a loose connection, and damaged or corroded terminals.
Is a concern present?
Yes No REPAIR as necessary.
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.GO to DZ25. - DZ25 CHECK FOR LEAKS IN THE EXHAUST SYSTEM
- Visually inspect the exhaust system for the following:
- exhaust leaks at flanges and gaskets
- HO2Ss not tightened to specification
- physical exhaust system concerns
- aftermarket exhaust
- punctures or cracks in the catalytic converter
Is a concern present?
Yes No REPAIR as necessary.
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.GO to DZ26. - Visually inspect the exhaust system for the following:
- DZ26 CHECK FOR POTENTIAL SENSOR CONTAMINATION CONCERNS
- Investigate the following items as potential sources of universal HO2S contamination:
- use of unapproved silicon sealers
- fuel contaminated by silicon additives
- excessive oil consumption
- glycol leaking internally in the engine
- lead-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.
INSTALL a new Universal HO2S sensor. REFER to the appropriate Electronic Engine Controls article. .
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.INSTALL a new Universal HO2S sensor. 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. - Investigate the following items as potential sources of universal HO2S contamination:
- DZ27 CHECK THE UO2SPCT CIRCUIT FOR AN OPEN CIRCUIT IN THE HARNESS
- Ignition OFF.
- Universal HO2S-Front connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) PCM Connector, Harness Side UO2SPCT UO2SPCT
Is the resistance less than 5 ohms?
Yes No For DTC P2626 or P2629, GO to DZ31.
For all others, GO to DZ28.REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DZ28 CHECK THE UO2SPCT CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) PCM Connector, Harness Side (-) UO2SPCT Ground
Is the resistance greater than 10K ohms?
Yes No GO to DZ29. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- DZ29 CHECK THE UO2SPCT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) Universal HO2S-Front Connector, Harness Side (-) UO2SPCT Ground
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. GO to DZ30. - DZ30 CHECK THE RESISTANCE OF THE LABEL RESISTOR IN THE UNIVERSAL HO2S
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Component Side (-) Universal HO2S-Front Connector, Component Side UO2SPCT VPWR
Is the resistance between 3.5K - 999.9K ohms?
Yes No For DTCs P164A or P164B, unable to duplicate or identify the concern at this time.
GO to PINPOINT TEST Z .
For DTCs P2627, P2628, P2630 or P2631, GO to DZ32.INSTALL a new Universal 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. - Measure the resistance between:
- DZ31 CHECK THE RESISTANCE OF THE CURRENT TRIM RESISTOR IN THE UNIVERSAL HO2S
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) Universal HO2S-Front Connector, Component Side (-) Universal HO2S-Front Connector, Component Side UO2SPCT UO2SPC
Is the resistance between 25 - 330 ohms?
Yes No For DTCs P2626 or P2629, GO to DZ32.
For all others, RETURN to NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX for further direction.INSTALL a new Universal 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. - Measure the resistance between:
- DZ32 CHECK FOR CORRECT PCM OPERATION
- 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.