What does it mean?
P1195 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 (B1 S1) Circuit Insufficient Activity .
Symptoms
- Check engine light on
- Engine stays in open loop and runs rich, with a strong exhaust smell
- Poor fuel economy and reduced power
- Rough idle and hesitation on acceleration
- Emissions monitors never complete
- Catalyst codes may appear later if rich running continues
Likely causes
- Aged or contaminated oxygen sensor that no longer switches
- Failed sensor heater, so the element stays too cold to generate a usable signal
- Exhaust leak upstream of the sensor flattening the signal with outside air
- High resistance or an open in the signal or sensor ground wiring
- Corroded connector or a terminal with poor contact
- Sensor element poisoned by coolant, oil or the wrong sealant
- Persistent rich or lean running that holds the signal at one end of its range
How to fix it
- Bring the engine to full operating temperature and graph the sensor voltage; a healthy upstream sensor swings repeatedly between rich and lean
- Force a rich condition and a lean condition and check whether the sensor responds at all
- Test heater element resistance and its supply voltage, since a cold sensor cannot switch
- Check signal and ground wire continuity and resistance back to the module
- Inspect the exhaust manifold, gaskets and sensor bung for leaks that dilute the sample
- Look at the sensor tip for oil, coolant deposits or white ash indicating poisoning, and fix the underlying cause
- Replace the oxygen sensor once wiring, heater and exhaust test good, then confirm switching activity and closed loop operation