Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post - Secondary O2 sensor needed for Cruise control?

DJCarbine · 05-09-2013, 10:19 AM

Backstory first...

Removed my secondary O2 sensor from my Borla UEL and installed a wideband sensor in its place. I have an ECUTEK tune, so I figured that the secondary oxygen sensor checking is removed and I thought nothing of it.
The next day I start the car and begin to drive. The CEL comes on after a few minutes, and when I press the cruise control on/off switch the cruise control light comes on but will NOT turn off. The wideband is also reading a rich air/fuel ratio (13.2) at idle when the car should be in closed loop (fully warmed up etc.)
Its almost as if its stuck in open loop or some sort of catalyst self-test mode where it runs rich at idle and doesn't use primary O2 sensor to trim fuel

WOT shows normal A:F of low 13's so I believe the wideband is getting accurate readings.

Does the ECU need the secondary O2 hooked up for some reason?
I know there was a thread stating that you don't need the secondary (as is common on older OBD-II cars), but it is creating some strange problems for me.

Anyone with any input?

05-09-2013, 10:19 AM	#1
DJCarbine Thupercharged Join Date: Mar 2013 Drives: 2013 FR-S Location: La Grange Park, IL. Posts: 1,501 Thanks: 116 Thanked 751 Times in 439 Posts Mentioned: 23 Post(s)	Secondary O2 sensor needed for Cruise control? Backstory first... Removed my secondary O2 sensor from my Borla UEL and installed a wideband sensor in its place. I have an ECUTEK tune, so I figured that the secondary oxygen sensor checking is removed and I thought nothing of it. The next day I start the car and begin to drive. The CEL comes on after a few minutes, and when I press the cruise control on/off switch the cruise control light comes on but will NOT turn off. The wideband is also reading a rich air/fuel ratio (13.2) at idle when the car should be in closed loop (fully warmed up etc.) Its almost as if its stuck in open loop or some sort of catalyst self-test mode where it runs rich at idle and doesn't use primary O2 sensor to trim fuel WOT shows normal A:F of low 13's so I believe the wideband is getting accurate readings. Does the ECU need the secondary O2 hooked up for some reason? I know there was a thread stating that you don't need the secondary (as is common on older OBD-II cars), but it is creating some strange problems for me. Anyone with any input?