Before we start, It’s important to note that Bank 1 is always after the bank where the number 1 cylinder is located. Thus on a Ford Pickup, Bank 1 is the passenger side bank, but on Chevy and Dodge pickups, Bank 1 is the driver side bank.
You need to know this or you’ll discover you’re working on the wrong sensor, so make SURE you know bank 1 from bank 2 before you start chasing any of these codes!!!
Bank 1 Sensor 1 is between the engine and the catalytic converter. Bank 1 Sensor 2 is the O2 sensor that is in the middle of the catalytic converter or right behind the FRONT catalytic converter – that’s the converter that’s closest to the engine.
So make sure you know exactly which sensor is which before you even start.
Bank 2 has a sensor 1 and a sensor 2 laid out the same way.
If you’re using an OBD-II scanner and it shows a P2238 code, here’s what you need to know about its possible causes and common symptoms so that you can troubleshoot it as soon as possible.
What Does the P2238 Code Mean?
The P2238 code is defined as “O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1.” This code will be a concern related to one of the circuits that operate a “wide band O2 sensor.” This kind of heated sensor is much more precise than the conventional type of O2 sensor and has different circuitry. This kind of sensor is used on later model vehicles, including hybrids with gasoline engines.
The operation of an A/F sensor is much different than a conventional O2 sensor.
The current polarity through the sensor actually reverses to reflect O2 content in the exhaust rather than simply switching from .2 to .8v the way the older O2 sensors do, and there are two separate chambers within the sensor.
Conventional O2 sensors must reach 600°F (315°C) and wide-band sensors, 1400°F (760°C) in order to be accurate.
An electrical switch operates the “pump cell,” as it’s called in this type of wide band O2 sensor The electrode of the “pump cell” runs from the calibration power supply to point C.
If the voltage of pump cell electrode 2 which is connected to point A increases to a higher level than the measured voltage at point C, a current is generated, and the oxygen is pumped from the measuring chamber. If the opposite is true, the current reverses. In other words, if the measured voltage at point A is lower than the voltage at point C, the current runs in the opposite direction and the oxygen is pumped into the measuring chamber.
Note: The P2238 code may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
What are the Possible Causes of the P2238 Code?
The P2238 code has several possible causes, including the following:
- A defective oxygen sensor
- Issues with the wiring or connectors
- Faulty PCM or PCM programming error
What are the Possible Symptoms of the P2238 Code?
Below are some of the most common symptoms of the P2238 code:
- Reduced fuel efficiency
- Less engine performance
- Engine misfires and runs rough
- OBD-II codes relating to lean/rich exhaust mixture
- Illuminated check engine light
How to Diagnose the P2238 Code
It’s hard to diagnose the underlying issue behind a P2238 code. Testing the oxygen sensor, wiring, or the PCM requires specialist equipment and knowledge. Also, accessing these components may be difficult for someone without experience. If you want to properly diagnose the issue that’s triggering this code, you should consult a trusted automotive professional.
The following video can give you a better idea of the diagnostic process:
How to Fix the P2238 Code
There usually isn’t a single cure-all for the problems that trigger an OBD-II code because these issues have many possible causes. To determine the right course of action, you must first get an accurate diagnosis.
Once you’ve identified what’s triggering the P2238 code, you can consult credible online repair resources and how-to guides for possible solutions. When it comes to troubleshooting and repairing diagnostic codes, you should always consult your vehicle’s repair manual.
Chilton repair manuals can also be useful. However, ALLDATA subscriptions are even better, as they provide detailed factory repair information for drivers who want to do repairs themselves.
If you don’t have a lot of experience diagnosing or fixing trouble codes, it’s best to consult a professional mechanic, so that you can avoid problems and more expensive repairs down the line.
Where to Get a New Oxygen Sensor for Your Vehicle
As mentioned above, there are several possible reasons why your vehicle could log this error code. But one of the most common is a malfunctioning oxygen sensor. As soon as your mechanic recommends replacing the faulty part, CarParts.com can help make shopping for a replacement quick and easy.
Save time and enjoy the convenience of shopping online by checking out our selection of oxygen sensors. Plug your car’s year, make, and model into our built-in vehicle selector to browse the products that match your vehicle’s specs. We source all items from the most trusted manufacturers in the industry, so you can rest assured that you’re only choosing from the best.
Don’t let faulty parts ruin your vehicle’s performance. Shop now, and get your ride back to tip-top shape in no time!
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