OFT & Rear O2 Sensor Failure - Can I Temporarily Disable Codes? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

nofferman · 07-08-2017, 09:07 PM

I'm running OFT v2.061 E85 UEL Stage 2 tune with a UEL catless header.

I was running at the track today and got a P0037 and P0141 check engine codes, putting the car in limp mode and ending my day:

P0037 - HO2S Heater Control Circuit Low Bank 1 Sensor 2
P0141 - O2 Sensor Heater Circuit Malfunction

I metered the two black wires on the rear O2 sensor (black connector), and it's reading open resistance / dead. I'm about to go pull off the undertray and see if there's any visible damage to the sensor or wires. I've had no luck finding a replacement O2 sensor on the weekend so I can keep running tomorrow.

However, It looks like I can disable those codes in RomRaider.

My question is - will the dead rear O2 sensor affect the engine performance on an OFT tune, or is it just to check cat efficiency? If I disable those codes and re-flash it for just tomorrow, will the engine run properly? I'd like to get one last day in, but not at the expense of an engine.

Thank you!

phrosty · 07-08-2017, 09:16 PM

The O2 sensor does affect perf in subtle ways, consensus seems to be that it's safe to street so long as everything else is good, but I don't know if that translates to HPDE safety.

steve99 · 07-08-2017, 10:52 PM

Quote:

Originally Posted by nofferman

I'm running OFT v2.061 E85 UEL Stage 2 tune with a UEL catless header.

I was running at the track today and got a P0037 and P0141 check engine codes, putting the car in limp mode and ending my day:

P0037 - HO2S Heater Control Circuit Low Bank 1 Sensor 2
P0141 - O2 Sensor Heater Circuit Malfunction

I metered the two black wires on the rear O2 sensor (black connector), and it's reading open resistance / dead. I'm about to go pull off the undertray and see if there's any visible damage to the sensor or wires. I've had no luck finding a replacement O2 sensor on the weekend so I can keep running tomorrow.

However, It looks like I can disable those codes in RomRaider.

My question is - will the dead rear O2 sensor affect the engine performance on an OFT tune, or is it just to check cat efficiency? If I disable those codes and re-flash it for just tomorrow, will the engine run properly? I'd like to get one last day in, but not at the expense of an engine.

Thank you!

as well as disabling the cel codes you will need to set the AF#3 (rear 02 sensor) learning limits to zero theirs three tables see here, alse fueling will go weird when your cruising on highway.

http://www.ft86club.com/forums/showp...78&postcount=4

aagun · 07-09-2017, 12:19 AM

Also ilde AFR target to 13.8 .. for 30s then back to Normal

nofferman · 07-09-2017, 01:13 AM

Thank you for all of your quick replies. I think tomorrow is off. After getting under the car, there's a couple other things besides the O2 sensor that are questionable. Looking like it's smarter to get everything fixed up properly, add a couple other mods I've been wanting, and go back another time.

Thanks again!

steve99 · 07-09-2017, 05:07 AM

If wiring melted otr sgorted, you will likely have blown fuse called EFI HTR.

nofferman · 07-09-2017, 11:37 AM

Just checked it, EFI HTR fuse #29 is good.

It's possible that the wire was broken from contact with a brake duct, as it runs close to the header there and sits very snug against both O2 sensors. It's been OK for 2-3 years but it's time to find a more reliable solution for that too.

07-08-2017, 09:07 PM	#1
nofferman Member Join Date: Apr 2013 Drives: BRZ Location: Wisconsin Posts: 17 Thanks: 28 Thanked 7 Times in 5 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	OFT & Rear O2 Sensor Failure - Can I Temporarily Disable Codes? I'm running OFT v2.061 E85 UEL Stage 2 tune with a UEL catless header. I was running at the track today and got a P0037 and P0141 check engine codes, putting the car in limp mode and ending my day: P0037 - HO2S Heater Control Circuit Low Bank 1 Sensor 2 P0141 - O2 Sensor Heater Circuit Malfunction I metered the two black wires on the rear O2 sensor (black connector), and it's reading open resistance / dead. I'm about to go pull off the undertray and see if there's any visible damage to the sensor or wires. I've had no luck finding a replacement O2 sensor on the weekend so I can keep running tomorrow. However, It looks like I can disable those codes in RomRaider. My question is - will the dead rear O2 sensor affect the engine performance on an OFT tune, or is it just to check cat efficiency? If I disable those codes and re-flash it for just tomorrow, will the engine run properly? I'd like to get one last day in, but not at the expense of an engine. Thank you!

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07-08-2017, 09:16 PM	#2
phrosty Senior Member Join Date: Apr 2013 Drives: 2013 FR-S Location: Seattle Posts: 806 Thanks: 202 Thanked 320 Times in 199 Posts Mentioned: 18 Post(s) Tagged: 1 Thread(s)	The O2 sensor does affect perf in subtle ways, consensus seems to be that it's safe to street so long as everything else is good, but I don't know if that translates to HPDE safety. __________________ 2013 Whiteout 6AT FR-S \| Perrin Inlet Tube + 2.75" CAI \| OpenFlash Header \| P&L Catback \| 4.88 Final Drive \| Dialed in OFT 2.0x Stage 2 E85 \| 18x8 Enkei Raijin + 225/40 Michelin Pilot Super Sport \| 17x7 Stock + 215/45 Michelin X-Ice Xi-2

07-09-2017, 12:19 AM	#4
aagun Senior Member Join Date: Nov 2012 Drives: 86 Location: uae Posts: 403 Thanks: 202 Thanked 67 Times in 56 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	Also ilde AFR target to 13.8 .. for 30s then back to Normal

07-09-2017, 01:13 AM	#5
nofferman Member Join Date: Apr 2013 Drives: BRZ Location: Wisconsin Posts: 17 Thanks: 28 Thanked 7 Times in 5 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Thank you for all of your quick replies. I think tomorrow is off. After getting under the car, there's a couple other things besides the O2 sensor that are questionable. Looking like it's smarter to get everything fixed up properly, add a couple other mods I've been wanting, and go back another time. Thanks again!

07-09-2017, 05:07 AM	#6
steve99 Banned Join Date: Dec 2013 Drives: FT86 Location: Australia Posts: 7,998 Thanks: 1,035 Thanked 4,987 Times in 2,981 Posts Mentioned: 598 Post(s) Tagged: 2 Thread(s)	If wiring melted otr sgorted, you will likely have blown fuse called EFI HTR.

07-09-2017, 11:37 AM	#7
nofferman Member Join Date: Apr 2013 Drives: BRZ Location: Wisconsin Posts: 17 Thanks: 28 Thanked 7 Times in 5 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Just checked it, EFI HTR fuse #29 is good. It's possible that the wire was broken from contact with a brake duct, as it runs close to the header there and sits very snug against both O2 sensors. It's been OK for 2-3 years but it's time to find a more reliable solution for that too.

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