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Oxygen sensors are mounted in the exhaust manifold or located downstream from the manifold in the exhaust pipe. They monitor the amount of oxygen in the exhaust and send this information to the vehicle’s powertrain control module (PCM). The PCM uses this data to calculate and adjust the amount of fuel injected into the engine.

P0041 is one of the several on-board diagnostic (OBD) trouble codes related to a possible fault in oxygen sensor signals. Read on to learn more about this code.

What Does the P0041 Code Mean?

Diagnostic Trouble Code (DTC) P0041 stands for “O2 Sensor Signals Swapped Bank 1 Sensor 2/Bank 2 Sensor 2.” This code is set once the PCM detects that the wiring of the oxygen sensors downstream from the catalytic converter may have been swapped or crossed.

The PCM uses data from the upstream oxygen sensors to calculate how much fuel needs to be injected into the engine. Meanwhile, the module primarily uses the signal from the downstream sensors when calculating catalytic converter efficiency unless the upstream sensors become unreliable, because protecting the catalytic converter from overheating due to ultra-rich exhaust is considered of paramount importance.

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The ECM/PCM can detect whether the oxygen sensor wiring have been swapped based on a simple logic test. If the PCM injects more fuel into bank 2 of the engine but notices that the bank 1 oxygen sensor is reacting instead of the sensor on bank 2, it will set code P0041. Rationality checks are typically applied here. If the upstream sensors react one way and thd downstream sensor react in the opposite way, the fault is triggered.

Although P0041 is a generic code, it is considered uncommon. It may only appear on vehicles with more than one bank of cylinders.

A Quick Note About Light-off Catalysts

light off catalysts diagram
Diagram showing light-off catalysts | Image source: Richard McCuistian

The bank 1 sensor 2 and bank 2 sensor 2 O2 sensors monitor oxygen storage capacity of the light-off catalysts, which are the ones closest to the engine because they need to heat up very quickly. The downstream (sensor 2) O2s  are only used for fuel trim correction if the upstream O2 sensors between the catalyst and the engine are determined to be unreliable.

The bank 2 sensors typically only appear on V-configured multi-bank engines, although some in-line 6 engines (like the Jeep 4.0L) have the front three cylinders identified as bank 1 and the rear three cylinders as bank 2.

But Bank 1 is always where #1 spark plug is, so make sure you know which bank is which before troubleshooting a single sensor.

Note: The definition of code P0041 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 P0041 Code?

Here are some common causes of the engine code P0041:

  • Oxygen sensor #2 wiring connectors are swapped from bank to bank
  • Crossed, damaged, or shorted O2 sensor #2 wirings
  • Malfunctioning PCM
See also  P0131: O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)

What are the Common Symptoms of the P0041 Code?

Here are the common symptoms associated with this code:

vehicle check engine light illuminated clear look
An illuminated check engine light is a common symptom of the P0041 Code.

Note by Richard McCuistian, ASE-certified Master Automobile Technician: Decreased engine performance, rough running/idling, and increased fuel consumption almost never occur, however, with downstream sensor faults.

How to Diagnose the P0041 Code

Diagnosing a P0041 code can be tricky without the proper tools or know-how needed to identify what is causing the problem.

If you’re not well-versed in auto repair, it is best to leave the job to a professional. However, if you would like to diagnose this code yourself, we recommend consulting a vehicle-specific repair manual or an online repair database for the proper diagnostic procedure.

How to Fix the P0041 Code

Troubleshooting a P0041 code is no easy task, but if you’re up for the challenge, here are some common repairs you can try on your own: 

Fix Any Swapped Connectors

If you recently had any repairs done to your O2 sensor, then you might be dealing with swapped O2 sensor connectors. Perform a visual inspection of O2 sensor #2 to check if the connectors are attached to the wrong bank. If they are, you’ll have to swap the wiring connectors to the correct position in order to remove the P0041 code. 

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Replace Damaged Wires

If the P0041 code persists after repairing the swapped O2 sensor connectors, then broken wiring might be to blame. You’ll have to replace any damaged wires, so visually inspect your vehicle for any twisted or broken wiring around your O2 sensor. You can also use a multimeter to check for short wiring. 

Repair PCM

A broken PCM is a rare thing, but if none of your wires or connectors are to blame, then it might be time to check your PCM. To do this, you’ll need a digital oscilloscope and a scan tool. 

Monitor your O2 sensor’s signal using both tools at the same time. If they don’t throw the same values, then your PCM is most likely at fault and needs replacing. 

Keep in mind that these common fixes won’t always work for every vehicle. If none of these repairs solve your P0041 code, then it’s probably time to pay a visit to your trusted mechanic.

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About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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