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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.

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

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

There is no universal fix for a P0041 code. The exact diagnostic and repair procedures for this code may vary depending on your vehicle’s year, make, and model. For example, repair procedures for a P0041 Audi code may prove different from a P0041 BMW code.

If you’re an advanced DIYer who’d like to try and fix this code yourself, we recommend consulting a vehicle-specific repair manual or getting a subscription to an online repair database.

Products Mentioned in this Guide

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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