Oxygen Sensor Emulator

[brucehowe]

Hey Gang,

Need some help with my 09 128i.
Year and a half ago installed AFE headers and cats as a lower cost alternative to OEM parts.
Was warned that I may get codes from downstream O2 sensors.
Was resetting and no service engine light for several months.
Now, light comes on a few miles after reset.

Has anyone had experience with an oxygen sensor emulator that prevents the codes?
Another alternative would be a spacer to set the sensor further back from the stream, but I'm not sure there would be enough room.

Any insight would be most helpful.

Thanks so much,
Bruce

[asbrr]

Originally Posted by brucehowe

Hey Gang,

Need some help with my 09 128i.
Year and a half ago installed AFE headers and cats as a lower cost alternative to OEM parts.
Was warned that I may get codes from downstream O2 sensors.
Was resetting and no service engine light for several months.
Now, light comes on a few miles after reset.

Has anyone had experience with an oxygen sensor emulator that prevents the codes?
Another alternative would be a spacer to set the sensor further back from the stream, but I'm not sure there would be enough room.

Any insight would be most helpful.

Thanks so much,
Bruce

I presume you have checked the actual sensors and they simply don't require replacement? If things were ok for several months and the codes only recently appeared, something has changed.

As an alternative, you may be able to have someone like BPC or other tuners help tweak the ECU to prevent the check engine light. I would however look to get a proper diagnosis of why the codes have appeared first.

[Jrfly9]

Hey Bruce,

First, have you pulled the code, what is the reading for?


I have been struggling to get my 128i to pass emissions for a few months now, I have the AA tune which turns off the Readiness monitors for 02 and Cats. In my state I can only have one monitor "Not Ready", so no bueno.

I have went back and forth with AA (they've been great) but it appears nothing they can do on the software end to help me.

I recently threw 02 spacers on and initially the 02 passed and the Cat failed (obviously). I am going to throw a new tune on that has the 02 on and the Cat off in hopes that it will pass.

I probably won't get to drive the car for the next two weeks but I can let you know if this works once I have a definitive result.

[rowsdower]

Everything you need to know about how and when the car tests for cat readiness. A useful document for someone with a failed cat living in a state that allows 1 not ready...

https://www.europeantransmissions.co...0Procedure.pdf

OP, it's possible you drive in such a way that it took months for the cat check to occur twice, so you wouldn't have had the SES light for several months. I know with the way I drive, it is very rare I'm driving below 3000RPM and below 60mph for long enough for the car to do the cat check. Or, you have a dead O2 sensor. It's very common if you mess with the headers. Are you looking to pass inspection or just keep the light from turning on? Both AA and BPC offer tunes that turn the SES light off, but won't pass inspection.

[brucehowe]

I generally look for advice but am seldom in a position to give it, so:

A follow up after 500 miles with no codes, in case someone else has this problem.

Codes were P0420 & P0430: Catalyst System Efficiency Below Threshold.

Sensors passed all tests on reader. No other problems.

aFe headers and cats were less restrictive. Logic is they are not as efficient and moving sensors a bit out of stream will fool them. Local auto parts guy said spacers work more often than not.

I went for: UroTuning O2 Sensor Spacer. A bit pricey, but well made (not that that matters much). More important, the angle and long thread with lock nut seemed to offer more flexibility in a tight location. UroTuning claimed about an 80% success rate.

Well, I got through emissions inspection. And, by putting together a drive cycle of my own after looking at others, I was able to get all systems in a state of readiness after less than 30 miles.

Hope this helps someone else out.