Want to remove/disable your rear O2 sensor without a CEL? Here's how..
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Want to remove/disable your rear O2 sensor without a CEL? Here's how..
A big thanks to mrfred, JustDSM, and bez for their insights on this.
For those of you who run catless, or prefer to use a wideband O2 sensor in the bung originally intended for the stock rear O2 sensor, here's a way to safely remove the O2 sensor without resulting in a check engine/service engine light (trouble code).
Step 1
Unscrew and unplug your rear O2 sensor. Completely remove it from the vehicle.
Step 2
Disable the Rear O2 routine in the ROM
Step 3
Simulate the O2 heater
**A ROM-based heater disable method may be identified in the future which will remove the need for the hardware simulation described in Step 3. Until then, this is the best solution that I've found.**
All done! Enjoy.
**Update**
mrfred has posted an updated version of the software patch for ver 15 IX ROMs here and l2r99gst has posted the simulation patch for version 96940011 (2005) here. These patches, and patches for other ROM versions, are available as part of the tephra mod patches as well.
**Update**
Some have reported difficulty getting the aforementioned resistor setup working properly without a CEL and without generating too much heat. This ECU circuit requires an ohm load between 1.1 and 80 to keep the CEL from coming on (thanks mrfred!). The configuration you see below should work well to keep within the proper parameters and keep heat to a minimum.
For those of you who run catless, or prefer to use a wideband O2 sensor in the bung originally intended for the stock rear O2 sensor, here's a way to safely remove the O2 sensor without resulting in a check engine/service engine light (trouble code).
Step 1
Unscrew and unplug your rear O2 sensor. Completely remove it from the vehicle.
Step 2
Disable the Rear O2 routine in the ROM
- Update the ECUFlash XML file located at: C:\Program Files\OpenECU\EcuFlash\rommetadata\mitsubishi\evo\ 88590015.xml
using FrontPage or other XML editor to include the following entry so the code ends like this:
<table name="ECU Periphery0" category="Misc" address="faa" type="1D" level="1" scaling="Hex16"/>
</rom> - Open ECUFlash v1.3 and version 15 ROM image. Scroll down to the Misc section and locate the "ECU Periphery0" entry.
- If the value for this entry is "0x56DA," press "=" on your keyboard and type "0x56D8" (without quotes) and press Enter. If the value for this entry is "0x56DB," press "=" on your keyboard and type "0x56D9" (without quotes) and press Enter.
- Save the ROM image and flash your ECU with the new file.
Step 3
Simulate the O2 heater
- Locate the stock rear O2 electrical plug under the passenger seat, and find the O2 heater wires (red with a yellow tracer, and blue with a yellow tracer as seen below)
- Using a 10kohm/.25 amp resistor (found at RadioShack for $3..pack of 10), jump the heater wires creating a 10kohm resistance between them. You may find it useful to trim the resistor leads so that it fits down into the plug snugly.
- Use a ziptie to secure the resistor onto/into the plug.
**A ROM-based heater disable method may be identified in the future which will remove the need for the hardware simulation described in Step 3. Until then, this is the best solution that I've found.**
All done! Enjoy.
**Update**
mrfred has posted an updated version of the software patch for ver 15 IX ROMs here and l2r99gst has posted the simulation patch for version 96940011 (2005) here. These patches, and patches for other ROM versions, are available as part of the tephra mod patches as well.
**Update**
Some have reported difficulty getting the aforementioned resistor setup working properly without a CEL and without generating too much heat. This ECU circuit requires an ohm load between 1.1 and 80 to keep the CEL from coming on (thanks mrfred!). The configuration you see below should work well to keep within the proper parameters and keep heat to a minimum.
Last edited by Pd1; Jun 30, 2008 at 04:01 PM.
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If you have a xede /w smart, the knock box has a front o2 sim built in so no need to do any of this for the 8 just wire in the o2 harness to the box and your set!!
for all the xede haters
for all the xede haters
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this patch currently disables the CEL, but also prevents the readiness code from being set. Without this, you will not pass emmissions.