What's involved
What this repair actually is.
The downstream sensor sits after the catalytic converter and watches whether the converter is doing its job — a lazy or dead one sets catalyst monitor codes and can wrongly condemn a healthy converter. We replace it with a new OE-quality sensor and confirm the catalyst monitor reads correctly afterward.
Symptoms
How you can tell.
- Check engine light with a Sensor 2 code
- P0420/P0430 code with a converter that tests fine
- Failed emissions inspection
- Catalyst monitor will not set ready
If you delay
A dead downstream sensor blocks the catalyst monitor from completing, which alone can fail your NY inspection.
Educational estimate. Real pricing depends on your vehicle, the inspection, parts availability, taxes, and shop rates. Use this as a guide while you shop quotes.