Yellow Engine Light On then Off

[MTD]

Had the yellow engine light come on over the weekend on my E86, had been sitting in stationary for some time when I felt the tickover flucturate a bit and then driving off a few minutes later the light came on (handbook states emmisions out of limits). Car drove fine fine and the next day having driven most of the way home the light went off on start up. Once home I ran my Creator 310 and it showed codes 2371 DME Electronics box fan actuation and code 2073 DME Oxygen sensor emmission control.
The display on the reader has damage on the extreme left so the second digit of both faluts may be wrong. I can't find either of these codes listed either looking for the wording or trying variations of the code numbers.
Can anybody confirm what these fault codes mean?

 

[smorris_12]

The DME fan is literally that, a fan to cool the electronics, so that may be worth looking at alternatives for (it could of course be broken!)

The second, if correct, would mean a lambda sensor which would tie in with stumbles and emissions errors.

 

[MTD]

Thanks Scott. Sorry basic questions but where is the DME unit? Also if its the lambda sensor wouldn't this show up as an extra fault code?

 

[MTD]

Well I've done a bit more digging and established that the codes were 2F71 for the DME fan and 2C78 for the oxygen sensor. Amber light is still off and having cleared the two codes, but only the DME fan comes back.
As the fault code relates to activation of the fan, I assume it is dependant on temperature of the DME unit. Does anyone know if the DME actually gets hot enough in the UK to need the fan? Also where is the fan located?
I have also checked the live running of the lambda sensors, the before cat ones seem to work in unison and show around 2.0v, but the after cat ones show number 1 at 0.09v and number 2 at 0.74v, with mixture adaption of 0.17mg/s and 0.32mg/s. So it looks like one of the after cat sensors is faulty but does anyone know which one is wrong?

 

[smorris_12]

I've always wondered whether we get such fans. I've never thought to look!

According to Google it's bank 2 post cat but I've no idea which bank is which (I've always assumed bank 1 is cyl 1-3 but never looked into it.)

 

[colb]

Bank1 are first three cylinders from front to back Bank 2 are the remaining rear three. Follow the exhaust sensor wires up from the sensor to top of cam cover where they are clipped on to ID which is which. Before condemning lambda sensors ensure you have no split or holed vacuum pipes and intake boots. Air leaks will affect exhaust sensors and fuel trims if unmetered air is getting in causing the car into thinking it's running lean. As a consequence it will demand more fuel to be injected to richen the mixture will add up to 20%ote fuel till it gives up and sets the EML to draw attention to the fault. Smoke test will find any leaks you can't find visually.

 

[enuff_zed]

The DME fan is mounted up above the GM5 behind the glove box. It blows air through a hole into the main electrical box in the back left corner of the engine bay where the DME sits.

 

[MTD]

Thanks for all the info guys.
Have just been looking at the paper work I got with the car when I brought it, and found the it had a similar fault last year and the bank 1 post cat sensor was replaced so it looks like the other is the sensor may have died.
Need to get under the car tomorrow to see if this is something I can do if it needs to go to a garage.

 

[colb]

Best of luck getting it out space is limited ensure you have an exact fit ring spanner to get it moving had trouble using a a cut away lambda socket it rounded the sensor off ended up cutting top of sensor off with an air chisel then used an extractor socket to get it out.

 

[MTD]

Yes I read the thread about the agravation you had removing yours.
Have just removed the undersheild and established that the bank 1 sensor has been changed, also established that it looks beyond my capabilities to change the faulty one so will book it in to my local garage for them to do it.

 

[Mike6]

Your creator reader should indicate which sensor is at fault so strange that it isn't, may possibly be fault elsewhere as has been suggested. Take it from me the post cat sensors are virtually impossible to remove so wise choice to get a garage to do it.

 

[MTD]

Yes having established the fault code is 2C78 that indicates bank 2 post cat as the faculty sensor.

 

[MTD]

Just finish off the thread. Fault codes checked by the garage and sensor changed all for an hours labour charge so if it stops raining can be out and about in it this weekend.