P2197 Code: O2 Sensor Signal Biased/Stuck Lean (Bank 2, Sensor 1)

A vehicle’s engine is a powerful machine. Every component, sensor, and process needs to be precise so it can perform at its peak. If even one electrical component or sensor goes bad or malfunctions, it may have dire consequences.

Take the oxygen (O2) sensor, for example. This device monitors the oxygen levels in the exhaust as it leaves the engine. Too little oxygen in the exhaust indicates the engine is running rich. Too much oxygen in the exhaust indicates the engine is running lean and the P2197 code can register in your vehicle’s memory.

What does this code stand for and how do you know if this is the issue you’re specifically dealing with? This short guide will give you what you need to know about this specific diagnostic trouble code.

What Does the P2197 Code Mean?

Diagnostic trouble code (DTC) P2197 stands for “O2 Sensor Signal Biased/Stuck Lean (Bank 2, Sensor 1).”

Your vehicle’s powertrain control module (PCM)makes use of oxygen sensors to keep track of the air-to-fuel ratio. The oxygen sensor sends a voltage signal that indicates whether the fuel mixture is rich or lean to the PCM.

The PCM helps keep the air and fuel levels at the ideal ratio of 14.7:1 to keep the engine running at its optimal state. Too little oxygen means that the engine is running rich. Too much oxygen means that the engine is running lean.

DTC P2197 gets set when the PCM detects that the air-to-fuel ratio is too lean. This code may also mean that the air-to-fuel ratio has gone too far from the ideal ratio of 14.7:1 that the PCM cannot correct it anymore.

Also, an O2 sensor that is biased or stuck lean will always be reading below the mid-point and the ECM typically has decided it can’t be trusted, so a code is stored.

The OBD code 2197 specifically refers to the oxygen sensor between the engine and the catalytic converter, not the one behind it. The “Bank 2” in this trouble code’s definition refers to the side of the engine that does not contain the #1 cylinder.

Note that for some vehicles like many Toyotas, this code is referring to Air/Fuel ratio sensors or A/F sensors. These sensors are basically more sensitive versions of O2 sensors.

If you’re planning to troubleshoot P2197 yourself, you can find more technical information in our discussion about rich/lean codes, as well as how the air/fuel mixture can cause OBD codes to appear.

What are the Possible Causes of the P2197 Code?

Most OBD-II codes have several potential causes, and the P2197 code is no different. Below is a list of some of the most probable reasons the engine code P2197 registers in your vehicle’s memory:

• Damaged or corroded O2 sensor circuit wiring/connectors
• Faulty bank 2 heated O2 sensor 1
• A fuel delivery issue (e.g., low fuel pressure)
• Vacuum leaks
• Dirty or faulty mass airflow sensor
• Exhaust leak
• A/F sensor relay failure
• ECT sensor malfunction
• An issue with the PCM

What are the Common Symptoms of the P2197 Code?

There are a few warning signs that you might have an OBD code 2197 on your hands. Listed below are some symptoms that you should look out for:

• Check engine light illuminates
• Low engine power
• Engine misfires
• Engine running rough

How to Diagnose the P2197 Code

Proper diagnosis is key to resolving any OBD-II code effectively. Because there are quite a handful of causes for the P2197 code, giving a proper diagnosis may prove challenging.

Nowadays, there are a lot of resources that can help the average DIYer resolve trouble codes. Repair guides and online tutorials are just some of these resources. Below are a couple of video resources you can use to refresh your knowledge on the P2197 code.

How to Fix the P2197 Code

As mentioned above, an effective repair plan for OBD-II codes relies heavily on proper diagnosis. However, diagnosis steps and fixes will differ depending on the vehicle. It’s important to arm yourself with accurate and reliable information before attempting any repairs.

If you’re a regular DIYer, it’s good to invest in a good repair manual or any similar technical subscription in case you encounter OBD-II codes such as P2197. Although, if you don’t have much confidence in your repair skills, you can go to your local mechanic to have the job done for you.

Other Notes About P2197

Typically, the P2197 code will not prevent your vehicle from running, but it will result in reduced fuel economy. If you ignore this code or leave it unsolved, it can cause serious damage to the engine and its surrounding components, such as the catalytic converter.

Note that this code is similar to P2195, P2196, and P2198. If multiple DTC codes appear along with the P2197, it’s recommended to fix them in the order they appear.

Products Mentioned in this Guide

Oxygen Sensor Catalytic Converter