Possible Causes

This DTC uses two-trip detection logic. DTC is set when response of A/F sensor becomes deteriorated when vehicle is being driven at 25 MPH or more with engine at normal operating temperature and engine speed of 1500 RPM or more. Possible causes are:

• A/F sensor circuit is open or shorted.
• Defective A/F sensor.
• Air induction system malfunction.
• Improper fuel pressure.
• Defective fuel injector.
• Vehicle has run out of fuel.
• Defective ECM.