Short Term Fuel Trim (B2-S2) and (B1-S2) showing ---% No Values

[lahermano]

Hi All:

I have BMW X5 e53 2005.
I am running into the problems with fuel trims. Sensor 2 on both banks show --% .
I did replace all 4 Brand new OEM Oxygen sensors and still shows these values. Primary problem i am having is the Oxygen Heater Monitor is not getting finished. That led me to replace all 4 New sensors. Please help with ideas.. ?
** NO CHECK ENGINE CODES and car runs great.**

The OBD2 scanner shows
Short Term Fuel Trim (B2-S2) ---%
Short Term Fuel Trim (B1-S2) ---%
Short Term Fuel Trim (B2-S1) 6.2%
Short Term Fuel Trim (B1-S1) 6.0%
Oxygen Sensor Output Voltage (B2-S2) 0.755v
Oxygen Sensor Output Voltage (B2-S1) 0.160v

[Bdc101]

What are you scanning these codes with?


Also what engine do you have?

[lahermano]

i have the 3.0L X5 2005 and i am using the BlueTooth AutoPhix OBD2 scanner and using iphone App AutoPhix and this is the data stream screenshot.
The problem i have is the heated oxygen sensor monitor is not getting ready.
So replaced all 4 brand new OEM Bosch sensors.

[X5chemist]

Try a different scanner. A regular ODBII scanner should show rear sensor data.

[andrewwynn]

S2 not used for fuel trim only for worn out cat. Are you saying that your emissions monitor not clearing? Are you getting a fail or just n/a or not ready? Some if the monitors can take a really long time

[lahermano]

Thanks all for the response.
I got the Oxygen sensor heater monitor now in finished status.
As one of the thread mentioned I disconnected the O2Sensor connectors and did a start let it sit idle for few mins and stop twice and resetting the codes.
Then all the monitors except EVAP got ready after few hours of normal local driving.

I'm not so worried about EVAP as it shouldnt stop me for SMOG and it will eventually turn on in a day or so.

I have been fighting this for almost few months... and now it all worked out.

[andrewwynn]

Heater error unplug was my invention. Apparently the computer measures the O₂ heater current when new and memorized it. Changing to a new sensor there's no "coding" to tell the ECU it's not the same O₂ sensor with a wildly different starting resistance.

I even wired in simulated resistors to simulate the proper resistance right in the required value no luck.

I don't know what inspired me to try unplug and run with no O₂ but it immediately cured the heater error.

It was driving me nuts for a month or more. I think that may have been the year I had to get a month extension!

Funny. That would probably work ok on a worn out sensor also.

If my hint helped you solve that error, I'm beyond thrilled. I'm over 10000 posts I get get solid feedback on about 1% so that's amazing.

The evap code takes a long time and I think almost every state will pass emissions as long as evap is pending not failed.

Win is a win! Woot woot!