BMW M5 Forum and M6 Forums banner
1 - 3 of 3 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter · #1 ·
Hey Guys,

Here goes my story:

I got an E64 2007 M6, a year ago I installed Supersprint headers and Race Cats. To install the secondary O2 sensors I had to extend the cable to fit on the Race cats way in the back, needless to say I got the CEL with INCREASED EMISSIONS! message on my Idrive and been having it ever since, as you all may agree with me it's the most annoying thing ever, and up till a month ago I thought it was showing because of my race cats sending out more emissions than the ECU values would permit.

So in November I took out my ECU/DME and went on a business trip to the States where I sent it to Dinan in California (I have stage I Dinan ECU tune) and asked them to install a software that would just ignore the readings from the secondary O2 sensors for increased emissions and they were kind enough to do just that, I came back home put in the ECU started up the car the CEL was gone....for 10 seconds that is! Then appeared again! That was so frustrating!
A month ago I decided to take the ECU out again and RESEND it to DINAN to double check if their software was correct, turns out it was correct they sent me back the ECU I plugged it in and obviously the CEL was STILL there that's when Dan (from Dinan Tech support) suggested that since ALL 4 O2 sensors went out simultaneously (as shown in the fault readings of my ECU pic attached) it must be and I quote:

"We checked your DME when it arrived and it did in
> fact have the correct software programmed on it. So we took a look into
> the
> possibilities of the o2 sensors reacting the way they are and we found it
> rather odd that they all shared the same fault. All 4 oxygen sensors are
> showing fault with the heater circuit. Our recommendation is to check the
> relay for this circuit, and the wiring for this circuit. One of the more
> common reasons to have problems with ALL the heater circuits is a tech
> welding on the exhaust system."
"The heater circuit in all the sensors shares either a ground, a relay or a
> fuse. The failure of one of these would cause all the sensors heater
> circuits to fail. That makes the most sense to me. Dan"


So having become the savvy E-box opener that I am, yesterday I got to the E box and checked for X8582 fuse box as you will see in the 2nd picture attachment it's the fuse box with 5 fuses, thankfully one 20A fuse was burned/broken I was happy to have finally got to the root of the problem, changed the fuse, put everything back in place and started the car, the CEL was still on, went for a drive to the gas station to heat up the engine, washed the car and on the way back home BOOM the CEL went off! Finally after over a year of agony with a yellow christmas light on my dash it had went away by changing a 10cent fuse.
The story doesn't end here unfortunately, at night I took the car out to a friend's place 30 min away spent a good 4 hours there and when I got back into my car turned it on...you guessed it, the diabolic CEL light came back on!

Today I opened the E box again (now a 4 min job for me) checked the 20A fuse and saw it was broken again...
Guys I need your help, your suggestions, your ideas to help a fellow M brother out of this :crying:
Could it be an open circuit somewhere that's causing the fuse to break? My intuition says it's the extended seconday O2 sensors cable? What do I need to look for, test, measure, cut? To solve this? What could be causing such fuse to break over and over?

Help? :confused:
 

Attachments

·
Registered
Joined
·
3,246 Posts
Could it be an open circuit somewhere that's causing the fuse to break? My intuition says it's the extended seconday O2 sensors cable? What do I need to look for, test, measure, cut? To solve this? What could be causing such fuse to break over and over?
One of your O2 sensor cables might be touching the exhaust, which could easily happen since your headers and cats have been changed.
The wiring has melted causing a short, and blowing the fuse.
 
1 - 3 of 3 Posts
Top