[topgun100]

Please can you kind folk help me out. I recently bought a 2008 e93 with little knowledge of its history - hopefully, I didn't get too badly ripped off.

It's driving ok but I have the following issues.

1. Current mileage at 91,000 miles / 146,450 km
2. Sooty exhaust
3. Quite strong petrol smell from the exhaust when cold and lots of steam. Head gasket ok.
4. Poor mpg - 17.5mpg (UK), though mostly urban driving
5. Rough idle, particularly when cold.
6. Was showing misfires on cylinders 5 & 6 (see image 2). I have an invoice from the previous owner showing coil pack 5 and all spark plugs changed 1000km miles ago. Cleared the error codes and they didn't come back.
7. Error 2B05 for Nox sensor heating did come back

I'm hoping just coil pack 6 needs to be changed but I'm not that lucky ��.

What should I do next? I was thinking of pulling the spark plugs to check for leaking injectors but is there something easier I can look for first?


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[0l0dom0l0]

I'm assuming this is an N53.

6 new plugs (or check they have used the correct plugs). Then 6 new matching coils (£10 each). Ideally a walnut blast.

You need a working NOX sensor so either a new NOX sensor or simply replace just the sensor on the end itself (if you are happy to solder the new one on). Alternatively use a NOXEM. I went for the second option (cost £40).

Then you need to delete all adaptions and follow the adaption re learn process properly on bimmerprofs.

And give it about 1500 miles. It should all be fixed then.

[topgun100]

Thanks - that's really helpful. Yes, it's n53.

Can you please tell me where I can buy new coils for £10 each - they're £22 or so at eurocarparts with pomo code.

And NoxEm for £40?? I'm seeing 370 euros with shipping on bimmerprofs.

[0l0dom0l0]

I got my bosh 0221504471 coils from Oipe Oils a year ago. I just checked the receipt, total was £96 for all 6 so £16 each (my bad). Looks like they've gone up a bit since then.

Sorry, I didn't get a NOXEM for £40, I bought a used NOX sensor from an X5 40d and cut the sensor off, then soldered it to my existing control unit as I had the same fault as you. The heating element has gone.

It saves spending £370 on a NOXEM or new sensor for diagnostic purposes. My used sensor latest about 12 months and the fault has now returned so I will need to get a NOXEM at some point.

As long as the sensor has the same number and colour of wires, they are interchangeable but you need to keep the control unit that is for your car.

[topgun100]

I wonder if the heater element failing is the result of another issue, like unburnt fuel or additives. There's a bit more info here https://bimmerprofs.com/damages-nox-sensor/

Do you find that with your nox heating element gone, your MPG is always poor or is it just until the exhaust heats up naturally?

[0l0dom0l0]

My MPG is always poor, but I have an aging nox cat code so the car never runs stratified mode. That is the other reason I need to invest in the NOXEM.

These cars just eat NOX sensors. They are so far down the exhaust they get battered with condensation which is probably what cooks the element after a while.

The failed sensor is usually what manifests as other issues like rough running and misfires, rather than the other way round.