Post cat O2 sensor questions

KCLe90 · 07-17-2019, 09:51 PM

I have recently put in brand new O2 sensors on my MMP CLDP's and having issues with cat codes. I tuned the car with a JB4 (BMS) backend flash and made sure the catted option wasn't selected, but I still get the codes. Do I even need the post cat sensors, and is that why plugs are included with these DP's? Thanks for the help.

type-dRew · 07-18-2019, 08:18 AM

The only code the flash keeps out is catalyst inefficiency, if its a heater code or something else then the sensor just needs replaced.

KCLe90 · 07-18-2019, 10:56 AM

Quote:

Originally Posted by type-dRew

The only code the flash keeps out is catalyst inefficiency, if its a heater code or something else then the sensor just needs replaced.

I get two CLDP detected codes from the car, would unplugging the post O2 possibly trick the car into thinking it's fine?

type-dRew · 07-18-2019, 11:20 AM

what are the codes?

And no, you need the rear o2s for fuel trims, so even if it did, you shouldn't unplug them

KCLe90 · 07-18-2019, 02:01 PM

29F4 and 29F5

KCLe90 · 07-18-2019, 02:09 PM

The MHD tune should've gotten rid of this but I don't know why it continues to pop up.

07-17-2019, 09:51 PM	#1
KCLe90 Enthusiast 14 Rep 56 Posts Drives: 2008 e90 335i Join Date: Apr 2019 Location: Lubbock, Texas iTrader: (0)	Post cat O2 sensor questions I have recently put in brand new O2 sensors on my MMP CLDP's and having issues with cat codes. I tuned the car with a JB4 (BMS) backend flash and made sure the catted option wasn't selected, but I still get the codes. Do I even need the post cat sensors, and is that why plugs are included with these DP's? Thanks for the help. __________________ RB Twos with high heat wastegates, MMP DPs, RB inlets, RB PCV valve and cap, BMS DCIs, BMS OCC, BMS BOV adapter, ER charge pipe, VRSF 7.5" race intercooler, Fuel-It! stage 2 LPFP, Forge diverters, JB4 w/ backend flash, Öhlins R/T adjustable coilovers, swift springs, stiffer anti-roll bars, M3 control arms, Vorshlag camber plates, Quaife limited slip differential.
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07-18-2019, 08:18 AM	#2
type-dRew Major 641 Rep 1,245 Posts Drives: 2009 335i xDrive Join Date: Feb 2019 Location: Newport MI iTrader: (0)	The only code the flash keeps out is catalyst inefficiency, if its a heater code or something else then the sensor just needs replaced. __________________ 2009 335i xDrive AT / 177k+ miles PSP 750ic / Fuel-It! Stage 1 / BMS CP / Sutphin Tuning / RFP E50 11.61 @ 117.5 New setup; Covid 19Ts on RFP 93 + ARM inlets, dp, VTT cp and PSP outlets
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07-18-2019, 11:20 AM	#4
type-dRew Major 641 Rep 1,245 Posts Drives: 2009 335i xDrive Join Date: Feb 2019 Location: Newport MI iTrader: (0)	what are the codes? And no, you need the rear o2s for fuel trims, so even if it did, you shouldn't unplug them __________________ 2009 335i xDrive AT / 177k+ miles PSP 750ic / Fuel-It! Stage 1 / BMS CP / Sutphin Tuning / RFP E50 11.61 @ 117.5 New setup; Covid 19Ts on RFP 93 + ARM inlets, dp, VTT cp and PSP outlets
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07-18-2019, 02:01 PM	#5
KCLe90 Enthusiast 14 Rep 56 Posts Drives: 2008 e90 335i Join Date: Apr 2019 Location: Lubbock, Texas iTrader: (0)	29F4 and 29F5 __________________ RB Twos with high heat wastegates, MMP DPs, RB inlets, RB PCV valve and cap, BMS DCIs, BMS OCC, BMS BOV adapter, ER charge pipe, VRSF 7.5" race intercooler, Fuel-It! stage 2 LPFP, Forge diverters, JB4 w/ backend flash, Öhlins R/T adjustable coilovers, swift springs, stiffer anti-roll bars, M3 control arms, Vorshlag camber plates, Quaife limited slip differential.
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07-18-2019, 02:09 PM	#6
KCLe90 Enthusiast 14 Rep 56 Posts Drives: 2008 e90 335i Join Date: Apr 2019 Location: Lubbock, Texas iTrader: (0)	The MHD tune should've gotten rid of this but I don't know why it continues to pop up. __________________ RB Twos with high heat wastegates, MMP DPs, RB inlets, RB PCV valve and cap, BMS DCIs, BMS OCC, BMS BOV adapter, ER charge pipe, VRSF 7.5" race intercooler, Fuel-It! stage 2 LPFP, Forge diverters, JB4 w/ backend flash, Öhlins R/T adjustable coilovers, swift springs, stiffer anti-roll bars, M3 control arms, Vorshlag camber plates, Quaife limited slip differential.
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