Are running w/o cats killing my O2 sensors?

[Haywood]

I know this has been discussed before, but I can't seem to figure out why it keeps happening to me. Ever since I went catless, I've had issues with engine malfunction errors and limp mode. After running the BPM diagnostics, it always comes back bank 2 and I replace my driver's side O2 sensor. Problem goes away.

Well, it's been about 9 months and just today I received the dreaded engine malfunction and limp mode. Ran the diagnostics and indeed it was bank 2 again. Fortunately, I purchased an additional Bosch 17039 sensor so I will do the swap tomorrow morning and see if it corrects the issue.

So, the question is: Does running catless somehow gunk up or ruin O2 sensors?

[BPMSport]

Only more serious o2 faults will cause limp mode.
Most o2 faults will just cause an increased emissions error but no limp mode. What were the actual fault codes?

[Haywood]

Originally Posted by Mike Benvo

Only more serious o2 faults will cause limp mode.
Most o2 faults will just cause an increased emissions error but no limp mode. What were the actual fault codes?

////////////////////////////////////////////////////////////////////
// BMW Trouble Code list
//
// ECU Type : Siemens DME MSS60
// Vehicle Manufacturer Ecu Hardware Number : 7848125
// Vehicle Manufacturer Ecu Software Number : 7848136
// Hardware Reference Number : 0569QT0Z240EEKEV0
// Vehicle Identification Number : WBSKG9C54DJ594987
// Ecu Manufacturing Date : 03.04.2013
//
// 1) 2789 Catalytic converter conversion bank 1
// 2) 278A Catalytic converter conversion bank 2
// 3) 2751 Lambda sensor error pump current cable VKAT bank 2
// 4) 2B39 Combustion misfire with cut-out cyl 5
// 5) 2B3A Combustion misfire with cut-out cyl 6
// 6) 2B3B Combustion misfire with cut-out cyl 7
// 7) 2B3C Combustion misfire with cut-out cyl 8
// 8) 2B41 Combustion misfire with cut-out several cyl
// 9) 2B57 Motor emergency programm activated
// 10) 2796 Motor emergency programm activated
// 11) 27C1 Info Tank leer bei Fehlereintrag
////////////////////////////////////////////////////////////////////

[BPMSport]

Could be bank 2 o2 or something else affecting bank 2 such as a throttle actuator.

[pbonsalb]

Your front 02 sensors measure the exhaust gas before the cats so nothing has changed in that respect. They are the 02 that provide input to the ECU.

The rear 02 are now seeing less clean exhaust but their only job is to measure how well the front cats did. They don't affect the ECU other than to trigger a code for emissions out of expected range.

Unleaded gas is fine for 02. Leaded gas, such as most race gas, will damage them over time.

[Haywood]

Originally Posted by Mike Benvo

Could be bank 2 o2 or something else affecting bank 2 such as a throttle actuator.

Thanks, Mike. I'll report back once I change the sensor.

[pbonsalb]

Swap bank 2 sensor 1 with bank 1 sensor 1. See if codes move to bank 1. Then you know its a front 02.

[Haywood]

Replaced bank 2 sensor. Started the car up and no SES light. Running like a champ again. But, it's still bizarre that I've gone through 3 sensors on that side now. Never an issue on bank 1. Thanks for the advice.

[BPMSport]

Originally Posted by Haywood

Replaced bank 2 sensor. Started the car up and no SES light. Running like a champ again. But, it's still bizarre that I've gone through 3 sensors on that side now. Never an issue on bank 1. Thanks for the advice.

You should clear the faults after replacement.

[jcolley]

The 2751 is indicative of a current fault in the sensor. It may be independent of the sensor itself such as the connector. Oxidization of the contacts, etc. The simple act of unplugging any plugging it back in may have jostled the wire enough to clear the fault.

It's extra work but if you put the old sensor you just took out back into bank 1, you may be able to determine if you localized the fault properly.

[AlpineE92M3]

I've been running catless for 2 years with BPM stage 2 on my '13. No problems here.

[Patrón]

are you replacing the faulty o2s with oem units or non oem? are you altering your gas with any type of octane booster or extra injector cleaners?

been catless on an ess tune for two years zero codes. I only use shell 93 gas and once a month or every other month a bottle of techron fuel additive.

[Haywood]

Originally Posted by Patrón

are you replacing the faulty o2s with oem units or non oem? are you altering your gas with any type of octane booster or extra injector cleaners?

been catless on an ess tune for two years zero codes. I only use shell 93 gas and once a month or every other month a bottle of techron fuel additive.

I'm using the OEM Bosch replacements. I always run 93 octane and try to use Shell or Exxon where I can.

[Patrón]

Originally Posted by Haywood

I'm using the OEM Bosch replacements. I always run 93 octane and try to use Shell or Exxon where I can.

that is crazy, i hope you resolve it and that it's not the damn actuators.

a friend went through a couple of 02s and one turned out to be defective, i was hoping you would post that you were buying different brands off ebay or amazon and not oem.