P1195 — O2 Sensor 1/1 (Bank 1 Sensor 1) Slow During Catalyst Monitor

Diagnostic algorithm

1. Retrieve and record codes, freeze frame and readiness status. Do not erase codes yet.
2. Warm the engine to normal operating temperature. Use a scan tool to view real-time O2 sensor (B1S1) voltage and switching pattern.
3. Verify heater operation: with ignition on (engine off) check for reference voltage/power and ground at heater terminal; measure heater resistance. Replace sensor if heater is open or out of spec.
4. Inspect connector and wiring for corrosion, breaks, chafing or poor pin contact. Wiggle wiring while monitoring sensor voltage to detect intermittent faults.
5. Check for exhaust leaks upstream of the sensor and repair if present.
6. Evaluate fuel trims, MAF/MAP and fuel pressure to rule out systemic causes of slow sensor switching (e.g., rich/lean conditions that prevent normal oxygen cycling).
7. If wiring and heater OK but signal is slow, substitute a known-good sensor or temporarily install a high-quality aftermarket sensor and re-run monitors.
8. If a replacement sensor fixes switching but the code returns, investigate upstream engine issues (fuel control, vacuum leaks, injector problems) and catalytic converter efficiency.
9. If wiring, sensor and engine systems check OK, consult OEM TSBs and software calibrations; consider PCM reflash as directed by manufacturer.
10. After repairs, clear codes, perform a drive cycle or use scan tool to run the catalyst monitor until ready. Confirm the fault does not return.