Possible Causes
WARNING: This page is about a different car, the 2003 Toyota Tacoma. 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 A/F sensor and heated oxygen sensor have nearly the same waveform pattern after engine and catalytic converter are at normal operating temperature and vehicle is driven. Possible causes are:
- Exhaust system leak.
- Defective A/F sensor (B1 S1).
- Defective heated oxygen sensor (B1 S2).
- Defective three-way catalytic converter (TWC).