Error Code P0040: What It Means & What To Do?

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Is your vehicle’s malfunction indicator lamp flashing? Is your vehicle showing a steep fall in engine performance? Is there a sudden rise in fuel consumption? If Yes, then chances are your vehicle is set OBD error code P0040. What is error code P0040? Well, to know that you will need to go through our subsequent sections.

OBD error code P0040 is a diagnostic trouble code (DTC). It is a generic OBD-II powertrain code as it applies to all makes and models. Though it applies to all, the repair mechanism may be different depending upon the manufacturers. OBD error code P0040 means that your vehicle’s PCM also known as the powertrain control module has detected an issue with the Oxygen sensors. It has detected that the first o2 downstream from the engine have swapped wirings.

This issue can be caused by multiple reasons which are listed below.

What Causes This Oxygen Sensors Signals Swapped?

• There is a swap between the connectors for bank 1 sensor 1 and bank 2 sensor 1
• There is crossed wirings of the oxygen sensors
• Failure of Electronic Control Unit (ECU)
• A Short or Open oxygen sensor wiring for bank 1 sensors

1. Oxygen Sensor - If your vehicle demands an oxygen sensor replacement, then you have arrived at the right place. We have in stock for you high end oxygen sensors from top brands like Denso, Bosch and many more
2. Mass Air Flow sensor - Need to undergo Mass Air Flow Sensor replacement? Worried about the cost? Well, you no longer need to worry about that as we have for you best priced MAF sensors in stock.
3. Manifold Absolute Pressure Sensor - Looking for manifold absolute pressure sensor for your vehicle make? If yes, then you can easily find that with us.
4. Powertrain Control Module - There is a chance are that your PCM, itself is damaged and is demanding for a quick change. So, what are you waiting for? Buy a new one with us now.
5. Engine Control Module - We also have in stock best in range Engine Control Module (ECM), you can find one for your vehicle at best prices ever online.
6. Fuel Pump - We have in stock high end fuel pumps for all make and models for you. So, what are you waiting for? Make the best parts yours today.
7. Catalytic Converters - If you need catalytic converters to fix this problem, all you need to do is to browse through our website. You can find the most budget friendly cat converters with us.
8. Diagnostic Tools - If you need any of the DIY diagnostic tools, to diagnose the issues with your cars. You can find them all with us.

Few of the common symptoms related to OBD error code P0040 are listed as follow:

Common Symptoms

• Illumination of check engine light
• Poor fuel economy
• Damage to cat converters
• Ecu entering the failsafe mode
• Rough running of vehicle
• Decline in engine power
• Flashing of MIL (Malfunction Indicator Lamp)
• Possible limp mode

We are sure nobody likes having a problem with their vehicles and we are sure you are no exception. If you wish to help your vehicle in getting rid of this issue you will need to undergo several potential repairs listed below.

• Installations of connectors on proper sensors
• Changing/Replacing the damaged wirings
• Replacing the defective ECU, if its beyond repairs

To correct this issue, you will definitely need new parts. Now where will you find these parts? Well if you wish to get the best parts at the best prices then we are your dream destination. You can find all the parts with us the most budget friendly prices.

Diagnosing a problem is not an easy task. While diagnosing your vehicle for any error code you need to be very careful and follow certain steps precisely. We have listed out few steps you need to follow to diagnose the OBD error code P0040.

• Firstly, you will start with a scan tool to confirm if your vehicle is actually set to OBD error code P0040 or not.
• Next, when you are certain that you are facing OBD error code P0040, a freeze frame data will be observed that tells what conditions the code was set under.
• Next, as we do it for all other codes, you will need to clear the code and conduct a road test. If the code returns you will need to perform a visual inspection.
• Next, once confirmed you will need to replace the connectors going to correct sensors.
• In case the connectors are all good, you will need to check the wirings visually. Make sure they are not open or shorted together.
• In case everything else fails you will need to conduct a visual inspection of the ECU.

Common mistakes when diagnosing the P0040 code

While conducting a diagnosis, committing errors is quite common. While diagnosing OBD error code P0040 make sure that the connectors are plugged into the right sides before you undergo an extensive diagnosis.

P0041 - Downstream Oxygen Sensors Swapped From Bank To Bank