What is OBD-II Code P22AC – O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 2

What is OBD-II Code P22AC – O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 2

If you have ever gone to your mechanic and heard them mention that your car is throwing a code, then it’s time to pay attention to what that code stands for. OBD-II codes are significant for modern vehicles because they help diagnose what’s happening with your car. OBD-II is a system that automakers use in their vehicles to monitor emissions from the engine, exhaust, and other important components of your vehicle. This system communicates to the driver through a light on the dashboard known as the Check Engine Light (CEL). When that light comes on, it tells you that something is wrong with your vehicle. In this article, we will explore OBD-II code P22AC, specifically, what it means, its causes, and how to remedy it.

What is OBD-II Code P22AC?

OBD-II Code P22AC – O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 2 is a code that indicates that there is a problem with the oxygen sensor on your vehicle’s exhaust system. Specifically, Bank 1 Sensor 2 is the Oxygen Sensor that is located after the catalytic converter. This code means that the positive current control circuit for the oxygen sensor is recording a lower than expected voltage.

The job of the oxygen sensor is to measure the amount of oxygen in the exhaust gas. It then sends a signal to the car’s computer which decides whether the engine is running too lean or too rich and adjusts the fuel mixture accordingly. The oxygen sensors are one of the most critical sensors in your car’s engine management system because they affect both the engine’s performance and emissions. Having a faulty oxygen sensor can cause your engine to consume more fuel and emit more pollutants.

What Causes OBD-II Code P22AC?

Several factors can result in OBD-II Code P22AC. These can include:

1. Wiring Issues: A faulty or damaged wiring leading to the oxygen sensor can cause disruptions leading to low voltage readings.

2. Malfunctioning Oxygen Sensor: Over time, oxygen sensors can wear out due to long-term exposure to high temperatures, vibrations and impacts they undergo from the vehicle’s movements. This impacts the sensor’s performance, and it may send wrong signals to the car’s computer system.

3. Failed PCM/ECM: The PCM/ECM controls signals sent to the sensors and adjusts the engine’s fuel mixture accordingly. When it fails, it can cause low voltage readings in the Oxygen Sensor, thus triggering the P22AC code.

4. Vacuum Leaks: Any vacuum leaks in the exhaust system can affect the oxygen sensor’s performance. This can lead to low voltage signals being sent, causing the P22AC code to appear.

How to Fix OBD-II Code P22AC

To fix OBD-II Code P22AC, you will need to start diagnosing the possible causes of the fault. A mechanic with an OBD-II scanner can help you identify the problem. Once you identify the problem, you can follow these steps to fix it:

1. Inspect Wiring Connections: One of the common issues that could cause this code is a bad wiring connection to the oxygen sensor. Check along the wire harness and look for any bare wires or damaged insulation. If there are, repair or replace the wiring connections to see if it fixes the problem.

2. Replace the Oxygen Sensor: If the wiring connections aren’t causing the problem, then it could mean that the oxygen sensor is faulty and needs replacing. At this point, a mechanic can identify the faulty sensor, remove it, and replace it.

3. Fix the Vacuum Leaks: If the oxygen sensor is not faulty, another possible cause could be vacuum leaks in the exhaust system. This can cause low voltage readings, so you should have it fixed to eliminate this possibility.

4. Replace the PCM/ECM: Finally, if everything else checks out and you still have the P22AC code appearing, the PCM/ECM may be the one causing the issue, and it will need to be replaced

Frequently Asked Questions About OBD-II Code P22AC

1. What causes OBD-II Code P22AC?

Code P22AC is caused by low voltage readings of the Oxygen sensor Positive current control circuit due to issues ranging from failed PCM/ECM, vacuum leaks, faulty Oxygen sensor, or bad wiring connections.

2. How do I diagnose OBD-II Code P22AC?

To diagnose OBD-II Code P22AC, you will need an OBD-II scanner to read, identify the specific code, and where it originated. After identifying the issue, you can inspect the wiring, replace the Oxygen sensor, eliminate vacuum leaks, or replace the PCM/ECM.

3. Can I still drive my car with OBD-II Code P22AC?

It’s generally not recommended to drive a car with a check engine light on due to the possibility of causing other problems to the engine or exhaust system.

4. Can a faulty Oxygen sensor affect fuel economy?

Yes, a faulty Oxygen sensor can affect fuel economy, causing poor gas mileage, reduced engine performance, and increased emissions.

5. How long does it take to fix OBD-II Code P22AC?

The time it takes to repair the P22AC code depends on the root cause and how easy it is to access and replacement parts. It can take anything from minutes to hours or even days if extensive repairs are needed.


There are various codes that your vehicle can throw, with P22AC being one of them. However, by understanding what this code means, what the possible causes are, and how to fix it, you can get your car back on the road and humming like new once again. While it may seem overwhelming at first, knowing what’s happening with your vehicle’s engine management system is crucial to keeping your car running efficiently and safely. Remember, seek the help of a trusted and experienced mechanic if you are unsure of the diagnoses or unable to fix it yourself.

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