Confusing codes: 279C and 28AE

[DaveP]

On a recent trackday I felt the car hesitate a bit under power, and got the above codes back from my Creator C310+ scanner. I cleared them, and the car has driven fine since, but I have the nagging feeling there's something brewing that could leave me stranded at a track in future. What's more confusing is that there were no lights on the dash, and no misfire recorded in the codes.



There's not much useful information available online about these codes appearing together on M54s, so I'm really struggling to work out what needs fixing. At a guess, I'd say that the water temp sensor had some kind of range reading issue caused by residual under-bonnet heat (although the gauge never moved from the middle), so had planned to change the sensor and thermostat for good measure.

Before I do this, does anyone have any smart suggestions? Is it possible that the second code was a result (torque limiting) of the first? Or are they completely unrelated?

 

[Zedebee]

I have the first code, no lights and no temperature issues. I do have a new thermostat waiting to go in just in case, but it doesn’t seem like an urgent issue. I guess it makes a difference whether your thermostat is stuck open or closed, but you’d soon know.

I do not have the second code but I doubt very much it’s related to the first.

 

[DaveP]

I have the first code, no lights and no temperature issues. I do have a new thermostat waiting to go in just in case, but it doesn’t seem like an urgent issue. I guess it makes a difference whether your thermostat is stuck open or closed, but you’d soon know.

I do not have the second code but I doubt very much it’s related to the first.

If my thermostat was stuck open, I'd expect it to take an age to warm up, and it doesn't. Stuck closed I'd imagine it would run very hot, but the gauge was pinned to the middle.

All very confusing...

 

[Zedebee]

Mine is the same. Could just be a faulty sensor.

 

[enuff_zed]

I'd suggest from previous discussion that the thermostat code is not likely to cause that hesitation, whereas anything that limits the torque is likely to do so?
No idea what the answer is, but logic suggests it is that second code you should be researching more.

EDIT: goggled 28AE DME and got dozens of hits. A brief look seems to say that this is your hesitation issue, but you'd need to read further.

If it is the DME dialling back power because it senses you are exceeding torque limits then it thinks it's working correctly so wouldn't show any misfire codes. How it calculates that I have no idea.

 

[Rockhopper]

I'd try a more advanced diagnostic tool as well. BMW Scanner on a laptop would probably give more information.

 

[DaveP]

I'd suggest from previous discussion that the thermostat code is not likely to cause that hesitation, whereas anything that limits the torque is likely to do so?
No idea what the answer is, but logic suggests it is that second code you should be researching more.

EDIT: goggled 28AE DME and got dozens of hits. A brief look seems to say that this is your hesitation issue, but you'd need to read further.

If it is the DME dialling back power because it senses you are exceeding torque limits then it thinks it's working correctly so wouldn't show any misfire codes. How it calculates that I have no idea.

Which links did you find that made sense for 28AE? I just found lots of forum posts about non-M54-engined cars (including Minis) and a variety of diagnoses, but nobody seemed to suggest they'd solved the issue.

 

[DaveP]

I'd try a more advanced diagnostic tool as well. BMW Scanner on a laptop would probably give more information.

Annoyingly since clearing the code it hasn't come back. I'd be a bit frustrated if I had to go as far as more advanced tools. While the Creator is hardly the last word in diagnostics, I'd expect to at least be able to do/learn something with the codes it was throwing back at me.

 

[enuff_zed]

I'd suggest from previous discussion that the thermostat code is not likely to cause that hesitation, whereas anything that limits the torque is likely to do so?
No idea what the answer is, but logic suggests it is that second code you should be researching more.

EDIT: goggled 28AE DME and got dozens of hits. A brief look seems to say that this is your hesitation issue, but you'd need to read further.

If it is the DME dialling back power because it senses you are exceeding torque limits then it thinks it's working correctly so wouldn't show any misfire codes. How it calculates that I have no idea.

Which links did you find that made sense for 28AE? I just found lots of forum posts about non-M54-engined cars (including Minis) and a variety of diagnoses, but nobody seemed to suggest they'd solved the issue.

I didn't look that deeply as I'm supposed to be wfh. :roll:
Noticed they all had very similar symptoms though.
Possibly only happened due to sustained high revs in a track environment.