Fuel & air metering · Powertrain · generic (SAE-defined)
P2195: O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 1)
P2195 means the upstream oxygen sensor on bank 1 keeps reporting lean exhaust, and the computer cannot get it to respond as fuel is added.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P2195 sets
The powertrain control module (PCM) adjusts fuel based on the bank 1 sensor 1 oxygen or air-fuel sensor. If the signal stays on the lean side and does not respond even as the PCM adds fuel, the sensor is judged biased or stuck lean. Thresholds and test methods vary by manufacturer.
Common causes of P2195
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Faulty or aged bank 1 sensor 1 oxygen or air-fuel sensor
- Exhaust leak near the upstream sensor
- Vacuum or intake air leak
- Low fuel pressure or restricted injectors
- Wiring or connector fault in the sensor circuit
- Dirty mass air flow (MAF) sensor
P2195 symptoms
- Check engine light on
- Possible hesitation or rough idle
- Reduced fuel economy
- Often few drivability symptoms
How P2195 is diagnosed
- Scan for codes and freeze frame; look for P0171 or sensor heater codes.
- Review fuel trims to see whether the engine is truly lean.
- Inspect for exhaust leaks ahead of the sensor.
- Smoke-test the intake for leaks.
- Check sensor response by briefly enriching the mixture and watching the signal.
- Inspect wiring and check fuel pressure.
Typical fixes for P2195
- Replace the bank 1 sensor 1 oxygen or air-fuel sensor
- Repair exhaust leaks
- Repair vacuum leaks
- Fix fuel delivery problems
- Repair sensor wiring
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P2195 FAQ
What does code P2195 mean?
P2195 means the upstream oxygen sensor on bank 1 keeps reporting lean exhaust, and the computer cannot get it to respond as fuel is added. The standard definition is "O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 1)."
Can I drive with a P2195 code?
Generally yes for a short period, but have it diagnosed soon. The engine may actually be lean, or the sensor may be lying, and either can affect fuel economy and emissions.
Does P2195 always mean a bad oxygen sensor?
No. A real lean condition from a vacuum or exhaust leak can make a good sensor read lean, so check the system before replacing the sensor.
Which sensor is bank 1 sensor 1?
It is the upstream sensor before the catalytic converter on the side of the engine that has cylinder 1.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.