Cant Find Fuse P0050
 

My car: 08 e70 4.8
My problem: P0050 - Oxygen Sensor B2 S1: Heating Circuit: Malfunction/Open Circuit

I understand that a fuse may be bad. I have spend an hr looking for the darn thing and cant find it.
How dumb of a manufacturer not to have labeled the fuses (my 1st and last BMW, sounds like)... but I digress.

Would someone please help me.
I need to locate the fuse and test it before I get a new o2 sensor.
I have looked under the glove box but all 30amp fuses appear to be ok.
I am looking my mind. :(

Beers to one who helps me. Thank You.



UPDATE: the write up is on 2nd page (sort of write up)

There's another fuse box in the right rear panel of the truck. Tucked to the side of the fuse box is a guide to what each fuse covers.

is there an E-box in the engine bay? some fuses, relays could be there

I have located two fuses, 40Amp, located under the cabin air filter.
Both are good.

As for other fuse panels... I have one in under glove box and one in the back passenger side next to tail light. I have no documents tucked in anywhere, my guess is previous owner has removed it.

Can someone scan their fuse layouts and email me or post on line.

I appreciate the help.


I will continue troubleshooting tomorrow.

How did you diagnose the fuse bad? Did you measure the voltages at the connection to the O2 sensors and find no voltage?

This error is most common when an O2 is unplugged or a wire ripped.... on the E39 the fuse is under the ebox/air filter and is NOT well marked/documented.

Again, measure voltages at the O2 connection first, THEN look for fuses.

I had codes 2C9C and 2C61 which were for Lambda probe heater front catalyst, control and Lambda probe front catalyst, electrical error. Ended up replacing the passenger side pre-cat sensor and all is well. I do a lot of DIY work and the pre-cat sensors on the V8 engine are a royal pain because of their location.

Stopped by the dealer today and they said that I cant buy a replacement card with fuses listed on it.

If anyone has all fuse listing and layouts, please post them or email me the scans directly. My email -> [email protected]

Just sent you pictures of the diagrams to your e-mail. If that doesn't work, send me a PM with your cell # and I'll send them to your phone. BTW, make sure you look closely for the card. It is neatly folded and tucked in the right side of the rear fusebox. It's really hard to find. All you see is a little tab sticking out.

?

UPDATE:

at the end of the day the problem was a bad O2 Sensor.

Wow, BMW could not make it any harder and more difficult to get to it and replace it.
Not only did I have to find a little boy to get to the O2 sensor, now I am gonna have to feed him Benihanas.

After driving over 500 miles this weekend all is well.

If it was a pre-cat sensor, I feel your pain! Been there and done that. Had to use the old sensor harness to slide the new sensor down from the top and then there's still barely room to get the threads started.

Yes, that pas painful.
Again, wow!, what a genius spot to place the o2 sensor. :rofl:

How did you diagnose it finally?

Did you find the fuse (in case anyone else in the next 10 years is searching.......)

A

To keep it short,
All my testing was comprised of visual inspection and some continuity testing.
I ended up pulling out and visually inspecting almost all fuses (I had no fuse pin-out -> used car)
I believe that fuses related to o2 sensors are located on passenger side in engine compartment and under cabin fresh air intake system, inside ecm box.
I pulled both fuses I found there (believe those to be 40A, inspected them visually and reseated them)
Farther, I looked at all wiring and to the sensor and determined it was not damaged, torn, broken... you get the idea.
A BMW tech, when hearing of the code I had, with certainty said the problem I had was a bad sensor.
I've purchased a replacement Bosh sensor at a local imports place since the price for it was 187 vs. 300 the dealer charges.

Here is the link to Fuse Panel Pin-out: http://www.xoutpost.com/bmw-sav-foru...tml#post942809




Here is what I had to do to replace the o2 sensor (bank 2, sensor 1):

Things to know (terminology and some blah, blah…)
-bank 1 = cylinder 1,2,3,4 or passenger side (black side - connectors are black on all sensors for this side)
-bank 2 = cylinder 5,6,7,8 or driver side (gray side - connectors are gray on all sensors for this side)
-sensor 1 = pre catalyst (catalytic converter) = upstream (in BMW speak) = sensor closest to the engine
-sensor 2 = post catalyst (catalytic converter) = downstream (in BMW speak) = sensor farthest away from the engine

sensor locations
- Bank 1, sensor 1 and sensor 2 are located and visible from under the vehicle on passenger side and from under the passenger seat area (after you remove protective skid plate)
- Bank 2, sensor 1 and 2 are located and visible from under the vehicle on drives side and from under the drive seat area (after you remove protective skid plate)

Another helpful link: BMW Workshop Manuals - X Series E70 X5 4.8i (N62TU) OFFRD Workshop Manual - 3 RA Replacing Left Oxygen Monitor Sensor (N62 _ N62TU)


Work to be performed: (in no way I authorize you to do any of this work. Only a qualified BMW dealer can do this repair and you should let them)

Important: Scolding Hazard! get a Fan and place under the car to cool down the exhaust system before you start any work on it:
http://www.homedepot.com/catalog/pro...b6285e_300.jpg
Lasko 20 in. 3-Speed Box Fan-3733 at The Home Depot
- put car on ramps
- remove protective skid plate, the last plate located farthest back from the front
(order of skid plates: 1. plastic belly pan/cover; 2. metal oil filter area skid plate; 3. transmission skid plate)
- disconnect o2 sensor you are replacing (you can follow cables from each sensor. Sensor 1 connections are located under passenger seats inside a connector clipped housing)
- remove sensor 2 to allow your arm access to a clip holding cables for sensor 1
- top of engine: disassemble air intake remove two air intakes to air box
- remove top of air box
- remove both lower parts of air box
- remove rain gutter/tray on driver side
- remove center peace connecting drive side rain gutter to passenger side
- remove aluminum cross tie on driver side
- from bellow the vehicle loosen the o2sensor with a long open end wrench (unless you have an o2 wrench)
- find a little boy and place him on top of engine or get thin arms (lol!)
- o2 sensor can be reached from above engine drive side back of engine corner
- replace the sensor
- tighten sensor from bellow
- replace all parts in reverse order
- using an obdII scanner: reset ecm code
- restart the car and make sure everything runs