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Home › Chrysler › 1999 › Sebring JXi › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes - Convertible › Self-Diagnostic Tests › Test NTC-7: Checking For Oxygen Sensor Switching

Test NTC-7: Checking For Oxygen Sensor Switching

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Upstream oxygen sensor may also be referred to as 1/1 O2 sensor. Downstream oxygen sensor may also be referred to as 1/2 O2 sensor.
  1. Start engine and warm engine to normal operating temperature. With engine running, use scan tool to read oxygen sensor voltage for each oxygen sensor for at least 10 seconds. Downstream oxygen sensor voltage does not switch like the upstream oxygen sensor voltage, as downstream oxygen sensor voltage switches slower than upstream oxygen sensor voltage. If oxygen sensor voltage for each oxygen sensor is switching normally, test is complete. If oxygen sensor voltage for each oxygen sensor is not switching normally, go to next step.
  2. If upstream oxygen sensor remains locked on lean, go to next step. If upstream oxygen sensor does not remain locked on lean, go to step  10.
  3. Shut engine off. Turn ignition on with engine off. Using scan tool, read oxygen sensor voltage for each oxygen sensor. If oxygen sensor voltage is less than .1 volt for upstream or downstream oxygen sensor, go to next step. If oxygen sensor voltage is .1 volt or more for upstream or downstream oxygen sensor, go to step  8.
  4. Start engine and allow engine to idle. Check engine vacuum for abnormal vacuum reading. If vacuum is normal, go to next step. If abnormal vacuum reading exists, repair as necessary. Perform TEST VER-2A .
  5. Shut engine off. Disconnect connector at the appropriate oxygen sensor in which the oxygen sensor voltage was less than .1 volt. On 2.4L, upstream oxygen sensor is located on the exhaust manifold. On 2.5L, upstream oxygen sensor is located on exhaust pipe, just above the catalytic converter. On all models, downstream oxygen sensor is located on exhaust pipe, behind catalytic converter.
  6. Ensure ignition is off. Disconnect connectors at PCM. PCM is located at driver's side front corner of engine compartment, just below air cleaner assembly.
  7. Resistance should be checked on circuit for oxygen sensor in which the voltage was less than .1 volt. Using ohmmeter, check resistance between ground and terminal No. 4 (Black/Dark Green wire) for upstream oxygen sensor or terminal No. 1 (Tan/White wire) for downstream oxygen sensor on wiring harness side of connector for oxygen sensor. If resistance is 5 ohms or more, replace appropriate oxygen sensor. Perform TEST VER-2A . If resistance is less than 5 ohms, repair short to ground on Black/Dark Green wire for upstream oxygen sensor, or Tan/White wire for downstream oxygen sensor between PCM and oxygen sensor. Perform TEST VER-2A .
  8. Start engine and allow engine to idle. Check engine vacuum for abnormal vacuum reading. If vacuum is normal, go to next step. If abnormal vacuum reading exists, repair as necessary. Perform TEST VER-2A .
  9. With engine idling and at normal operating temperature, use scan tool to reset adaptive fuel memory. Use scan tool to read oxygen sensor voltage for each oxygen sensor for at least 10 seconds. Downstream oxygen sensor voltage does not switch like the upstream oxygen sensor voltage, as downstream oxygen sensor voltage switches slower than upstream oxygen sensor voltage. If oxygen sensor voltage for each oxygen sensor is switching normally, oxygen sensors are operating properly and test is complete. If oxygen sensor voltage for each oxygen sensor is not switching properly, perform TEST NTC-4: CHECKING ENGINE MECHANICAL SYSTEMS .
    10. WARNING: Fuel system is under high pressure and fuel pressure must be released before opening fuel system.
  10. Shut engine off. Release fuel pressure. See FUEL PRESSURE RELEASE  procedure. On 2.4L, connect fuel pressure gauge to fuel pressure test port located at center of fuel rail. On 2.5L, disconnect fuel supply line quick disconnect fitting at chassis fuel supply line located near front (timing belt end) of engine. Connect Fuel Pressure Adapter (6539) and fuel pressure gauge between fuel supply line to fuel rail and chassis fuel supply line.
  11. On all models, turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure to stabilize. Using scan tool, stop ASD fuel system test. Monitor fuel pressure for one minute.
  12. If fuel pressure does not decrease to less than 10 psi (.7 kg/cm2 ), release fuel pressure. Remove test equipment. On 2.5L, reinstall fuel supply line. On all models, go to next step. If fuel pressure decreases to less than 10 psi (.7 kg/cm2 ), release fuel pressure. Remove test equipment. On 2.5L, reinstall fuel supply line. On all models, check for defective fuel pump or fuel lines. If fuel pump and fuel lines are okay, replace leaking injector(s) as necessary. Perform TEST VER-2A .
  13. Inspect air cleaner and inlet ducts for restrictions. If no restrictions exist, perform TEST NTC-4: CHECKING ENGINE MECHANICAL SYSTEMS . If air cleaner or inlet ducts are restricted, repair as necessary. Perform TEST VER-2A .
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