P2238 OBD Error Code: Problem & Solutions

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The issues you were facing with driving had something to do with the P2238 code that is set in your vehicle. But don’t worry, we are here to help you know about this code and also how to repair and resolve it. The P2238 is an OBD-II code which is defined as a O2 Sensor Positive Current Control Circuit Low. The Powertrain Control Module of your vehicle will set this code when it detects a problem with the oxygen sensor of your vehicle. This is the reason why the check engine light is also on, it helps the driver to know that something needs to be fixed.

As you have understood the P2238 code is set by the PCM due to an issue with the oxygen sensor. You may be wondering what the job of the oxygen sensor is, well, it measures the amount of oxygen present in the exhaust gasses once they have been let out after the combustion has taken place. This code is related to an issue with the O2 sensor for bank 1 sensor 1 when it has a short circuit for the heater control circuit present in the O2 sensor. You shouldn’t take this code lightly and proceed to diagnose it soon.

What causes this problem with the O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1?

• Problematic oxygen sensor/s
• The wiring and/or connectors of the sensors aren’t proper
• Issue with the PCM or presence of a PCM programming error

It is vital to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P2238 here:

Common Symptoms

• Fuel efficiency has dropped
• Lowered engine performance
• There are codes set which are related to engine misfire or lean/rich exhaust
• Check engine light is also on since the code was set

Want to correct the Trouble Code P2238? Read these points mentioned below:

• Check the O2 sensor for any short circuit in the heater circuit and repair or replace accordingly
• The wiring connector or wiring to the O2 sensor shouldn’t have any shorts, repair or replace to fix the problem
• Replacement of the power relay for the heater circuit because it has gotten burned out
• Repair any shorted circuit picked up by a pinpoint test, replace parts if needed
• Repair or replace the ECM depending on the damages present

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It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P2238 code to be stored:

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of reliable vehicle information to be able to perform diagnosis. Once they have them handy start your diagnosis by collecting all the codes that have been stored. To do this connect your OBD-II scanner to the vehicle diagnostic port and retrieve all the codes stored, and freeze frame the data. Make note of all these codes as well. Once you have done that clear the codes and go on a test drive. If the code doesn’t set and the PCM enters readiness m0doe, it’s an indication of intermittent condition being present, in such case you will have to wait for the condition to worsen before proper diagnosis can be drawn.

If the code returns, then continue the diagnosis. Collect all the vehicle information you need for diagnosis, like diagnostic flow charts, connector face views and pinout charts, component location diagrams etc. Keeping them handy for reference start a visual inspection of the HO2S related wiring and connectors, all the damaged wiring and connectors will have to be either repaired or replaced. You can do this based on the extent of damage. Once you have finished fixing them move on and unplug the HO2S with the issue and using the DVOM check the resistance present between the positive current control circuit and any ground circuits. If you pick up continuity then there may be an issue with the HO2S. Repair or replace, clear the codes and go on another test drive.

If the P2238 code is set again, then start the engine and let it come to normal operating temperature and be in idle. Now connect the scanner again and observe the input data from the O2 sensor visible on the data stream. If the sensors are working fine then the voltage on the pre-cat O2 sensors will range between to 900-millivolts with the PCM in loop operation. The post-cat sensors will be in this range; however, they will settle down after a point and be stable in comparison to the pre-cat sensors. HO2S which are not able to cycle properly will have to be considered defective, if the engine is in good condition. A low battery voltage or no voltage displayed by the HO2S on the data stream of the scanner may be displayed. In this case using the DVOM get live data on the HO2S connector. If the output data is the same then there is most likely an internal short in the HO2S. In such a case replacement will be compulsory.

Common Mistakes When Diagnosing the P2238 Code

• Presence of exhaust leak
• Oxygen sensor has failed
• Powertrain Control Module (PCM) is no longer working
• Wiring of the sensor is having problems