Possible Causes
WARNING: This page is about a different car, the 2003 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
This DTC uses two-trip detection logic. DTC is set when heated oxygen sensor (B1, S1) response time for the output voltage to change from rich to lean, or from lean to rich is 0.4 second or more during constant vehicle speeds with engine at normal operating temperature. Possible causes are:
- Heated oxygen sensor (B1, S1) circuit is open or shorted.
- Defective heated oxygen sensor (B1, S1).
- Air induction system malfunction.
- Improper fuel pressure.
- Defective fuel injector.
- Defective ECM.