P2195
O2 Sensor Signal Stuck Lean (Bank 1, Sensor 1)
The upstream oxygen sensor on bank 1 returns a constant lean signal during conditions where rich content is expected (for example after a deceleration fuel cut-off recovery). Usually a sensor that has lost its rich-side response or a slow heater warm-up.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Common causes
Ordered by how often each turns out to be the cause.
- Upstream sensor failed stuck leanCommon
- Sensor heater slow to warm upPossible
Parts involved
- Oxygen Sensor Upstream
- Oxygen Sensor Heater
P2195 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.