Oxygen O2 Sensor Removal / Delete: ECU Software service & Delete Kit

Secondary/Primary Oxygen Sensor Voltage

In diagnostic readings, the primary (upstream) oxygen sensor fluctuates between 0.1V (lean) and 0.9V (rich) as it continuously monitors the air-fuel ratio for the ECU to adjust fueling in real time. The secondary (downstream) oxygen sensor, located after the catalytic converter, maintains a steadier voltage—typically around 0.4V to 0.7V—indicating converter efficiency. If the downstream sensor mimics the upstream sensor's fluctuations, it may signal a catalytic converter failure. 

What are the benefits of deleting the O2 sensor?

Deleting the secondary O2 sensor is often necessary after installing performance headers, aftermarket downpipes, or removing the catalytic converter. This modification prevents false errors and check engine lights caused by altered exhaust flow, ensuring the ECU does not trigger limp mode or incorrect fuel trims. Additionally, an O2 sensor delete allows for custom ECU remapping, optimizing performance without interference from emissions-related restrictions. This is especially useful for off-road or race applications, where a fully functional secondary sensor is not required. However, it's essential to use an ECU remap, O2 sensor simulator, or delete kit to prevent diagnostic issues.

Can I delete my downstream O2 sensor?

Yes, you can delete your downstream O2 sensor, especially if you plan to install performance headers, a decat, or an aftermarket downpipe—in other words, if you are removing the catalytic converter. The second O2 sensor monitors the catalyst's efficiency, so without it, the ECU will trigger a check engine light (CEL) and possible error codes. To prevent this, you can remap the ECU using tuning tools like KESS 3, WINOLS, or ECM Titanium. If you want to delete your secondary O2 sensor, simply read your ECU file with a programmer, send it to our tuning file service, and we will provide you with a professionally remapped O2-off file in the shortest time.

Note: We don’t recommend removing the catalytic converter as it harms the environment. If you have a check engine light with DTC P0420 or P0140 and the catalyst is still installed, visit a dealership or mechanic for diagnostics. A faulty O2 sensor isn’t always the cause—issues like low-quality fuel can also trigger these codes. Always diagnose first before considering an O2 sensor delete.

What is a O2 sensor delete kit?

An O2 sensor delete kit is a device or simulator designed to bypass the secondary (downstream) oxygen sensor after removing or modifying the catalytic converter. It prevents the check engine light (CEL) and DTC errors like P0420 (Catalyst Efficiency Below Threshold) by mimicking the expected sensor voltage. These kits come in different forms, such as mechanical spacers (mini cats) or electronic simulators, tricking the ECU into thinking the catalytic converter is functioning properly. For a permanent solution, an ECU remap using tools like WINOLS, ECM Titanium, or KESS 3 can disable the sensor directly in the software.

How to delete the second o2 sensor from ECU?

Programmer to delete O2 sensor, follow these steps. 
1-     read the ECU file using a laptop and a professional programmer such as KESS3, KTAG, KESS2, or Autotuner. These tools allow you to extract the original ECU software for modification. 
2-    modify the file using software like WinOLS or ECM Titanium to disable the rear O2 sensor monitoring. If you're unfamiliar with map editing or want to speed up the process, you can send the file to our tuning file service, where our experts will make the necessary changes for you. Finally, 
3-    write the modified file back to the ECU using the same programming tool and perform a diagnostic check to ensure no error codes remain. This process ensures the secondary O2 sensor is fully deleted from the ECU’s system, preventing check engine lights (CEL) and optimizing performance for off-road or racing applications.

Second O2 Sensor OFF Delete Services

At Schiller tuning, we have over a decade of experience using WinOLS software to remap and modify ECU calibrations. We offer a wide range of professional tuning services, including remaps, DTC off, sensor off, DPF off, EGR off, AdBlue off and more, all at the best prices.

How to Disable the O2 Sensor with ECU Remap Services

1.    Read Your ECU File
Use a tuning tool to read your vehicle’s ECU file. This process can typically be done easily with an OBD-II interface or other tuning tools.
2.    Send Your ECU File to Us
Once you have your ECU file, simply send it to us for remapping. We provide a fast and efficient service to customize the file to your needs.
3.    Pricing and File Submission
For detailed pricing information and to submit your ECU file, visit Schiller-tuning.com.
4.    Receive Your Remapped O2-Off File
After processing, you will receive a remapped O2-off file. This file will disable the O2 sensor as requested, and it can be uploaded back to your ECU.
This simple, quick process ensures you can bypass your O2 sensor without hassle!
 

O2 Off Service Price

At Schiller tuning, we offer a professional O2 sensor delete service at competitive prices. The cost varies based on the vehicle’s ECU type and the complexity of the modification. Customers can simply read their ECU file with a tuning tool, send it to us, and receive a remapped O2-off file in the shortest time. For pricing details and file submission. visit Schiller tuning file service .

Rear O2 Delete Software

The rear O2 sensor delete is best done through ECU remapping software like WINOLS, ECM Titanium, or KESS 3. This process removes the sensor’s function from the ECU, preventing it from triggering DTC errors or adjusting fuel trims based on false readings. Unlike mechanical spacers or simulators, software deletion offers a permanent and error-free solution, ensuring no future issues with emissions-related diagnostics.

Pros and Cons of Second O2 Sensor Delete

✅ Pros:
•    Eliminates check engine light (CEL) and DTC errors (e.g., P0420, P0140).
•    Prevents the ECU from making unwanted fuel adjustments.
•    Allows for better tuning flexibility after installing headers, downpipes, or decat.
•    Permanent solution when done via ECU remap (WINOLS, ECM Titanium, KESS 3).
•    No need for O2 spacers or simulators that may not always work.
❌ Cons:
•    Not recommended if the catalyst is still in place—other issues may be causing fault codes.

Common Second O2 Sensor Errors and DTC Codes

The downstream O2 sensor monitors catalytic converter efficiency, and when issues arise, it triggers DTC errors and the check engine light (CEL). Common fault codes include:

•    P0420 / P0430 – Catalyst Efficiency Below Threshold (Bank 1 / Bank 2)
o    Triggered when the catalytic converter isn’t performing efficiently, often due to removal, failure, or exhaust leaks.
•    P0140 / P0160 – O2 Sensor No Activity Detected (Bank 1/2, Sensor 2)
o    Indicates the rear O2 sensor is not providing data, possibly due to sensor failure or ECU deletion.
•    P0138 / P0158 – O2 Sensor Circuit High Voltage (Bank 1/2, Sensor 2)
o    Caused by high sensor voltage, often linked to fuel mixture issues or missing catalyst.
•    P0139 / P0159 – O2 Sensor Circuit Slow Response (Bank 1/2, Sensor 2)
o    The sensor is responding too slowly, possibly due to contamination or faulty wiring.

If these codes appear after removing the catalytic converter, an ECU remap using WINOLS, ECM Titanium, is the best solution to disable the rear O2 sensor function and prevent errors.

Contact us: Contact us easily via WhatsApp at +45 55 22 92 98 

 Email: [email protected]   We’re here to help!