o2 Sensor Codes...
 

Good day Forum

I have had the following codes just pop up on my BMW X5 4.6is (146K)

17 o2 sensors 1 after
12 o2 sensors 2 after
14 o2 sensors 1 heater after

Does this mean I am now changing out all 4 of these little devils?

:dunno::dunno::dunno:

Not necessarily. If you are not sure that all codes popped up at once, I would clear the codes and see what comes back. If they did, my input would be that codes are the result of something else that is the core issue not the sensors. The pre cat sensor is part of the air/fuel mixture determination. The post cat sensor focus on emissions. I suggest troubleshooting the cause rather than replacing the sensor at this point. Do you know if the codes were generated during a cold start? Have you lost any engine performance, idling RPMs normal, engine missing? Even if all is fine, I would start troubleshooting by checking for vacuum leak.

ok so it has thrown these codes again after driving:
17 o2 sensors 1 after
12 o2 sensors 2 after

Car runs, drives, idles like a dream. No loss of power. Code didn't appear right at start.

How long after a cold start?

It occurs after the car is warmed and driven for at least 30 minutes.

Are you able to look at live data fuel trims?

:dunno::dunno::dunno:

I have an MT2500 but unknown if this has the capability. I reset and drove for about another 40 miles and it popped back on today ... code 17.

How (if it is possible) can I live data fuel trims?

Normally if the 02s after the cats are reporting a problem, it could mean the catalyst efficiency is not up to the design parameter. I would just take it to an auto part store that will scan the X for FREE. This way you can post some generic P codes that everybody can understand instead of the priority P code from a Snap-On MT2500 scanner. What does the Snap-On book say about the codes?

Ok put in my non BMW cartridges. Code P0140 02 pulled. Test revealed Bank 1 Sensor 2 Failed. All others passed.

B1 S1 calc (v) .745 min limit .475 max limit 1.005
B1 S2 1.025 .480 1.005
B2 S1 .810 .475 1.005
B2 S2 .820 .480 1.005

Both Min and Max Sensor Failed with Back 1 Sensor 2


Does this mean to replace only that O2 Sensor?

Since its showing higher AFTER the cat then I would think that sensor is bad or fowled.

Its usually high then low not low then high.