P2195: O2 Sensor Signal Biased/Stuck Lean (Bank 1, Sensor 1)

P2195 means the front oxygen or air-fuel sensor on bank 1 reports a lean mixture that the ECM does not believe, either because it stays lean or because it disagrees with other evidence. On GM's Bosch-based 2005 V6 the rear sensor has to read rich (above 0.85 V) while the front A/F sensor reads leaner than lambda 1.08 and the short-term trim sits at its maximum of 1.25, for about 100 s or 50 s in total. Ford checks narrow-band sensors for fewer than 5 switches in 30 s and wide-band sensors for 30 s at the short-term trim limit; from 2019 a sensor whose filtered lambda changes by less than 0.0001 for 30 s sets P2195 if the value is at or above 1. On the Opel/GM 2.0 turbo in the Saab 9-5 (2010) the code sets within 4 s continuously or 50 s in total. Ford replaced the heated oxygen sensors for P2195 and P2197 on 2015 to 2017 Explorer and F-150 3.5 GTDI. An exhaust leak ahead of the sensor can also make it read lean.

Medium severity. Can I keep driving?You can drive in moderation to a repair shop. Avoid straining the engine, especially if there is jerking, because with an actually lean mixture it can overheat and misfire.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank. Sensor 1 is the oxygen sensor before the catalytic converter.

Symptoms

Malfunction indicator lamp on
Possible rough running or higher consumption from wrong fuelling

Most likely causes

Front oxygen or A/F sensor aged or contaminated
Exhaust leak ahead of the sensor
Sensor signal or reference wiring fault

What to check, in order

Start with the simplest. You can tick off each step.

Check the wiring and connector of the sensor indicated
Use the scanner to command the movement and compare the actual position with the requested one.
Look for exhaust leaks
Check the signal in live data with the engine warm
Check the fuse and the heater resistance if the code mentions it
Replace the sensor if it has power and does not respond

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P2195 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
1: Air and fuel
95: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2195?

You can drive in moderation to a repair shop. Avoid straining the engine, especially if there is jerking, because with an actually lean mixture it can overheat and misfire.

What causes code P2195?

The most common causes are: front oxygen or A/F sensor aged or contaminated; exhaust leak ahead of the sensor; sensor signal or reference wiring fault.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.