Diagnostic Test

TEST FOR A RICH O2 SENSOR CONDITION
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. Disconnect engine vacuum lines to create a lean running condition.
4. With the engine vacuum lines disconnected monitor the O2 Sensor graph on the scan tool.
  Did the O2 Sensor graph show a change from rich to lean?
  
  Yes
  - Check for any of the following conditions/mechanical problems that can cause a O2 Sensor stuck rich condition:
  - AFTERMARKET equipment or software effecting emissions.
  - AIR INDUCTION SYSTEM - must be free from blockage.
  - ENGINE VALVE TIMING - must be within specifications.
  - ENGINE COMPRESSION - must be within specifications.
  - ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
  - ENGINE PCV SYSTEM - must flow freely.
  - FUEL - must be free of contamination.
  - FUEL INJECTOR - plugged, stuck open or restricted injector.
  No
  - Replace the Oxygen Sensor in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
TEST FOR A LEAN O2 SENSOR CONDITION
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. Create a rich running condition.
4. With the rich running condition, monitor the O2 Sensor graph on the scan tool.
  Did the O2 Sensor graph show a change from lean to rich?
  
  Yes
  - AFTERMARKET equipment or software effecting emissions.
  - AIR INDUCTION SYSTEM - must be free from leaks.
  - ENGINE VACUUM - must be at least 13 inches in neutral.
  - ENGINE VALVE TIMING - must be within specifications.
  - ENGINE COMPRESSION - must be within specifications.
  - ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
  - ENGINE PCV SYSTEM - must be free of leaks and flow freely.
  - POWER BRAKE BOOSTER - no internal vacuum leaks.
  - FUEL - must be free of contamination.
  - FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector.
  No
  - Replace the Oxygen Sensor in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .