[Serf27]

Hi everyone, I have an e90, 2008 328i that I'm working on and an "engine management" fuse keeps blowing.
I also have a code for each o2 sensor heater.

I've only found info on checking for loose wires grounding out and to check the 40 amp fuse in the dme box.

The 40 amp fuse in the dme box is fine, and receives power. Another thread said there was a small fuse box in the dme box, but I just see a single 40amp fuse, a relay and connectors.
Its the engine management fuse that keeps blowing once the accessory is turned on(30) amp fuse.
In this link, the first diagram (e90 type 1) it is fuse 35 in the fuse box.

I'm looking for help as to where the engine management wire may be so i can inspect it to see if its grounding out.

Thank you.

[Tunafish]

You sure you are looking at the right fuse box's? The one you are talking about is pre 03/2007 which would unlikely be in a 2008 vehicle. You should have type 3 as seen below.. Double check this..

[Serf27]

Thanks for the reply.
Hmm, you're right.
In the photo you posted, it is fuse 35 that keeps blowing.
In this link, "diagram type 2, since 2008" it lists fuse 35 as DSC.
https://fusesdiagram.com/bmw/fuse-bo...bmw-3-e90.html
I have no DSC lights. Those would pop up if that fuse was DSC related and blown right?

On the paper with fuse numbers and photos that's in the glove box, it lists fuse 35 next to the engine symbol, and another link I found had said engine management.
In this picture, it shows multiple fuses for the engine symbol, including fuse 35.
The car starts up fine and seems to run fine.

[Tunafish]

You sure its not fuse 38 of the one I pictured? That would be you o2 heaters.. First connection point x6011 would be a white with red strip.. This comes from fuse 38.

Then x6011 connects to x60551 and wire straight orange color would go to your o2 heaters...

[Serf27]

Thanks, you're correct on that. I was mixing up 35 and 38.
And the I codes I get are for all 4 o2 sensor heaters.

Thank you for the photo!
I should check for continuity between the fuse 38 prongs and the orange wire on connector x60551, correct? or do I have to pull out the entire fuse box and check from connector to connector?

If I have continuity there, can I check for continuity between the orange wire on connector x60551 and the orange wire on each o2 sensor connector?

does that sound right?

[SpeedBuggy]

Had a similar issue some years back with a 2008 328xi we owned at the time, not sure if related to your issue.

Check Engine Light on, faults for all O2 sensors.

Dealership diagnosed the car and found O2sensors to be good. Further check found a blown fuse (Fuse #4 underhood engine electronics), replaced it and the fuse immediately blew again. All lines and connections were good and found a short circuit in the Crank Case Heater Valve. Replaced the valve, a gasket along with a clip and fuse, good to go now.

Here are a couple of links to similar issue.

https://www.e90post.com/forums/showthread.php?t=1189058
https://www.e90post.com/forums/showthread.php?t=454747

[Tunafish]

Yeah you can check connectivity but i would trace wires from DME (connector under hood) to exhaust. See if one is melted and on a ground.. Could be melted and grounded on the exhaust.

To narrow it down you can pull plug x6011 and see if the white wire with red strip has resistance to ground.. If so you know that the short is between the fuse box and that plug.. With same plug disconnected you can do the same to the orange wire on plug x60551 and if you have low resistance then issue would be between that and the o2 heaters...

[gbalthrop]

See F38 Fuse Circuit for 2008 & Later E9x Models, attached to next post. Note that F38 provides power to EACH of the Four (4) O2 Sensor Heaters, AND to the Breather Heater.

There was a recall, 17V-683, RCRIT attached, which related to E9x vehicles, with N51 & N52 Engines, built between 2006 and 2011, which would include your 2008 328i, due to electrical fault, Short, in the Breather Heater.

While ANYTHING in the circuit could cause a short and blow F38, the Breather Heater would be MY focus.

George

[Tunafish]

Nice there was continuing of the wiring diagram that didn't specify where it went.. Looks like it goes to the breather heater..

[gbalthrop]

Attached as described in prior post.
George

[Serf27]

Originally Posted by SpeedBuggy

Had a similar issue some years back with a 2008 328xi we owned at the time, not sure if related to your issue.

Check Engine Light on, faults for all O2 sensors.

Dealership diagnosed the car and found O2sensors to be good. Further check found a blown fuse (Fuse #4 underhood engine electronics), replaced it and the fuse immediately blew again. All lines and connections were good and found a short circuit in the Crank Case Heater Valve. Replaced the valve, a gasket along with a clip and fuse, good to go now.

Here are a couple of links to similar issue.

https://www.e90post.com/forums/showthread.php?t=1189058
https://www.e90post.com/forums/showthread.php?t=454747

Thank you for the links! I didn't even see those when looking up this issue.

Originally Posted by Tunafish

Yeah you can check connectivity but i would trace wires from DME (connector under hood) to exhaust. See if one is melted and on a ground.. Could be melted and grounded on the exhaust.

To narrow it down you can pull plug x6011 and see if the white wire with red strip has resistance to ground.. If so you know that the short is between the fuse box and that plug.. With same plug disconnected you can do the same to the orange wire on plug x60551 and if you have low resistance then issue would be between that and the o2 heaters...

I checked both wires and there was no continuity to the ground, so I moved onto the breather heater hose.

Originally Posted by gbalthrop

See F38 Fuse Circuit for 2008 & Later E9x Models, attached to next post. Note that F38 provides power to EACH of the Four (4) O2 Sensor Heaters, AND to the Breather Heater.

There was a recall, 17V-683, RCRIT attached, which related to E9x vehicles, with N51 & N52 Engines, built between 2006 and 2011, which would include your 2008 328i, due to electrical fault, Short, in the Breather Heater.

While ANYTHING in the circuit could cause a short and blow F38, the Breather Heater would be MY focus.

George

Thank you for this! checking to see if the wires on the plug in the DME box were grounded(they weren't) I went to look at the sensor on the manifold. I decided to disconnect it, knowing if that wasn't the issue, I would be in an even bigger mess trying to reconnect it later.

I disconnected the breather hose heater, replaced fuse 38, cleared codes and started the car. No more codes and the fuse is not blowing anymore!
I didn't drive it yet. I've ordered the new vent, but can I still drive the car while the current vent is disconnected? Would there be any downsides to that?

[bmwbob89]

Check online with BMW see if you have the open recall.