Rear O2 sensor needed? (Catless downpipes)

Creamo3 · 07-17-2015, 08:15 AM

Hey Guys,

I just installed my Agency Power downpipes last night (what a PITA

) and realized after buttoning it all back up that the driver side rear O2 sensor is about 1-2 inches short of being able to connect. Here's my questions:

1.) Once I have my tuner update my tune to account for the O2 sensor check engine light, can I just remove the sensors all together and buy a plug for the bung? I believe the secondary sensors just monitor for cat efficiency and nothing else vital.

2.)If a sensor is needed, could anyone recommend a part # for a cheap replacement with longer wires?

mitch808 · 07-17-2015, 12:53 PM

I'm sure you can find an extension cable. Usually o2 sensors use a standard plug, then again, not seeing what BMW uses, who knows what those zany Germans used as a connector...

It's also possible, you need trace back the o2 sensor wires, and remove any straps on the wire, to give you more slack. This is extremely common, especially on products like Agency Power. (They have a TERRIBLE reputation in the Japanese import crowd for low quality)

As for tuning, it depends if you can remove it. But traditionally, NO. While you can tune a check engine light off, the sensor is still used for closed loop AFR corrections. The tune is NOT turning off the sensor, just disabling the CEL/MIL function.

Creamo3 · 07-18-2015, 08:27 AM

I'll have to scour the web to see if I can find an extension or cheap replacement. Trust me I tried to free us as much slack as possible, but to no avail. The overall quality of the downpipes isn't bad, but I still expect more out of ~$1500 downpipes, coming from the Evo world you could get a full turbo back for this price w/ v-band clamps.

I'm still waiting to hear back from the tuner (EuroCharge), but when I used to tune Evo's you could essentially disable the rear O2 sensor as it wasn't being used and when the car would go for emissions testing there was a background routine that forced that readiness check to "Pass". Typically the front O2 sensor is used for STFT corrections and the rear is used to correlate a difference between the front to determine catalytic converter efficiency.

Oh well, the joys of modding I guess

Quote:

Originally Posted by mitch808

I'm sure you can find an extension cable. Usually o2 sensors use a standard plug, then again, not seeing what BMW uses, who knows what those zany Germans used as a connector...

It's also possible, you need trace back the o2 sensor wires, and remove any straps on the wire, to give you more slack. This is extremely common, especially on products like Agency Power. (They have a TERRIBLE reputation in the Japanese import crowd for low quality)

As for tuning, it depends if you can remove it. But traditionally, NO. While you can tune a check engine light off, the sensor is still used for closed loop AFR corrections. The tune is NOT turning off the sensor, just disabling the CEL/MIL function.

mitch808 · 07-19-2015, 12:58 PM

Agency Power started in the early 2000's with knock off parts for the Subaru WRX crowd, literally buying the preferred brand name products, copying them, and reselling "their design," for less. They used low cost overseas production, and materials. It was so blatant back then almost comical. Short shifters would break in half at the welds, exhaust wouldn't fit properly, rust, etc. This was of course 10yrs ago. The name vivid racing should ring a bell, they are one in the same.

They later branched off to other makes/models, I think the EVO was their next focus. And as they are today, moving up market to things like BMW's and such.

As such, I have little faith in a company like that to have designed the exhaust properly. Perhaps the piping and welds are good, or good enough. But in this case, they misplaced the O2 bung apparently, not taking into account production variance. Or poor QC.

I did a quick and dirty google search for "o2 sensor extension." here is the first hit:
http://www.summitracing.com/search/p...sion-harnesses

There are a number of other hits on the results too.

Alternatively, you can always put in an O2 plug (common at all autoparts stores or even home depot (finding the right bolt size) and have a muffler shop weld a new bung on.

07-17-2015, 08:15 AM	#1
Creamo3 Private First Class 29 Rep 131 Posts Drives: 2012 Alpine White X5M Join Date: Mar 2015 Location: Chicago, IL iTrader: (0)	Rear O2 sensor needed? (Catless downpipes) Hey Guys, I just installed my Agency Power downpipes last night (what a PITA ) and realized after buttoning it all back up that the driver side rear O2 sensor is about 1-2 inches short of being able to connect. Here's my questions: 1.) Once I have my tuner update my tune to account for the O2 sensor check engine light, can I just remove the sensors all together and buy a plug for the bung? I believe the secondary sensors just monitor for cat efficiency and nothing else vital. 2.)If a sensor is needed, could anyone recommend a part # for a cheap replacement with longer wires?
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07-17-2015, 12:53 PM	#2
mitch808 Captain 107 Rep 994 Posts Drives: 2012 X5 35i Join Date: Mar 2014 Location: Seattle iTrader: (0)	I'm sure you can find an extension cable. Usually o2 sensors use a standard plug, then again, not seeing what BMW uses, who knows what those zany Germans used as a connector... It's also possible, you need trace back the o2 sensor wires, and remove any straps on the wire, to give you more slack. This is extremely common, especially on products like Agency Power. (They have a TERRIBLE reputation in the Japanese import crowd for low quality) As for tuning, it depends if you can remove it. But traditionally, NO. While you can tune a check engine light off, the sensor is still used for closed loop AFR corrections. The tune is NOT turning off the sensor, just disabling the CEL/MIL function. __________________ 2012 X5 xDrive35i Sport Activity - Alpine White - M Sport Package
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07-19-2015, 12:58 PM	#4
mitch808 Captain 107 Rep 994 Posts Drives: 2012 X5 35i Join Date: Mar 2014 Location: Seattle iTrader: (0)	Agency Power started in the early 2000's with knock off parts for the Subaru WRX crowd, literally buying the preferred brand name products, copying them, and reselling "their design," for less. They used low cost overseas production, and materials. It was so blatant back then almost comical. Short shifters would break in half at the welds, exhaust wouldn't fit properly, rust, etc. This was of course 10yrs ago. The name vivid racing should ring a bell, they are one in the same. They later branched off to other makes/models, I think the EVO was their next focus. And as they are today, moving up market to things like BMW's and such. As such, I have little faith in a company like that to have designed the exhaust properly. Perhaps the piping and welds are good, or good enough. But in this case, they misplaced the O2 bung apparently, not taking into account production variance. Or poor QC. I did a quick and dirty google search for "o2 sensor extension." here is the first hit: http://www.summitracing.com/search/p...sion-harnesses There are a number of other hits on the results too. Alternatively, you can always put in an O2 plug (common at all autoparts stores or even home depot (finding the right bolt size) and have a muffler shop weld a new bung on.
	Appreciate 0 Quote