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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.” The powertrain control module (PCM) may set this code if the voltage signal output from your oxygen sensors are too low.

The PCM uses oxygen sensors to monitor and regulate the air-fuel mixture. Oxygen sensors check how much oxygen is left in the exhaust gases. This lets the PCM know whether the engine is running on a lean or rich air-to-fuel ratio.

Changes in oxygen levels cause changes in the output voltage of the sensor. Voltage signal outputs from the oxygen sensor are lower when more oxygen is present in the exhaust, and higher when less oxygen is present.

o2 sensor in an engine
Your car’s PCM sets the P2238 code if the voltage signal output from your oxygen sensors are too low.

If the PCM detects that the voltage is too low and doesn’t fall into its programmed operating range, then a P2238 code will be stored and the check engine light will illuminate.

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:

mechanic holding obd scan tool
Other OBD-II codes related to lean/rich exhaust mixtures can signify that your vehicle is running on P2238 code.

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.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

File Under : OBD-II Trouble Codes Tagged With :
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