Diagnostic Aids
- Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/Special Tool) .
- The system will go lean if an injector is not supplying enough fuel.
- A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel, a plugged fuel filter, or a restricted fuel pipe.
- Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to Intermittent Conditions .