O₂ heaters have power any time the key is on. The DME pulls the ground low to turn them on.

There's a particular error for heater out of range that can be reset I developed a method for that but I can't remember if it's the circuit low error it cures. You might be able to search my thread on the topic I likely posted the codes.

Good call on the PRNDL in the dash! If the connector shorts out you'll likely get random output for the PRNDL. There's also numbers and I would have the dash show I was in 54th gear.

Also only some of the PRNDL would lights while going though the gears that was the first clue about the transmission selector switch being the main suspect.

Turned out thankfully to be the connector to it since on 3.0i, the switch is internal!

X5 Christmas lights - A troubleshooting thread.
 

Yes I know there's no L on e53 just learned it PRNDL and it sounds funny without the L.

54321PRND I think is the exact dash display.

If you have a scanner that will show the "L" pins coming from the transmission that's how I confirmed the selector switch was reading random values. I think there are 4 pins that basically use BCD to send a coded value for each position of the gear selector.

Only four position they could have used 2 pins binary so it's a mystery and wait until you see what crazy values represent the 4 selections

I was looking for a chart/table but couldn't find but rather than the logical 0001
0010
0011
0100

It's seemingly random

I will pull INPA codes tomorrow and report back.

Thank you! I will try and get a visual on it tomorrow and let you know what I find.

Also for anyone else following along I found andrewwynn's original thread on this: https://xoutpost.com/bmw-sav-forums/...h-3-0-a-2.html

The instrument cluster does not currently show what gear it's in. My uneducated guess is that it is not shifting at all and is in 4th gear or similar at all times while this has been going on. When moving it from my driveway to the street it had very little power. Reverse on the other hand seems to be fine.

For the heater wire voltage is this what you are referring to?

https://www.pelicanparts.com/techart...placement.htm#

I am not entirely sure this is related but I have previously used the climate control and I'm pretty sure the heating in the car works just fine, but I could test it again. I did notice that the climate control display is pixelated and I've been looking for a replacement...

Is this what you are referring to?
"I've found that if I'm getting heater errors I've been able to reset the DME O2 calibration by unplugging the O2 for two engine starts and plug them back in."

https://xoutpost.com/1159844-post7.html

https://r.tapatalk.com/shareLink/top...ink_source=app

Try my post of transmission failsafe issues and the final disposition.

Sent from Embassy network using Tapatalk

Thad's the procedure. The original post included more detail including I think the error code but if you are having any error code related to the heater I would do that trick. I've used it myself and about 3x people at xo followed the process with success.

The working theory is the DME records the current draw of the four O₂ heaters when new and as they wear, the current changes enough they are no longer in spec. Replace with new and the Ω of the new will be randomly different. If they aren't close enough to the Ω of the original it'll still be out of spec.

It was a WAG out of desperation but it for whatever reason worked.

I tried simulating the heater with varied resistance between 1-2 Ω before doing this trick and it didn't work.

Two months of O₂ heater error ended after the first time I did the trick above. I've never seen any tsb etc about it but I suspect there's a software tweak to tell the DME there's a new sensor.

Good find. I was looking for that exact post. That is very likely your issue. Fits the symptoms exactly and yes you get 1 fwd one reverse gear when xm failsafe kicks in.

The second time it happened to me I was splashed with snow slush on the freeway and it instantly happened.

It stayed in 5th fortunately so I was able to continue about 50 freeway miles, drove about a mile from the freeway in 4th and found a driveway with a high curb drove the front wheel past the drive onto the curb as a car ramp and using my bubble wrap style window shade I rolled under the car and shook the water out of the connector for instant fix.

I still owe [mention]srmmmm [/mention] a case of beer for that one! I think it cost him like $1500 for a dealer to find the problem but he was the one that clued me in. I was ready to pull the bottom off my transmission because the troubleshooting flow chart said it was the selector switch which on the 3.0 is inside!