Technical Car/Motor Issues > BMW 3-Series E90 - 04 3.0 Warning light on. action required? Miscellaneous
Thread Author: legacylad Replies: 10

 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - legacylad
Driving home tonight in my '04 BMW 330 the following engine warning light came on...''exhaust emission values have deteriorated. have the system checked''.
Please can anyone advise in simple terms the meaning, and importance, of this.
many thanks
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - Zero
Is it on all the time?

Its probably the oxygen sensor, either way it needs to be looked at.
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - legacylad
Thanks Z
It came on after 5 miles and remained on.
The cabin oxygen is ok because I could still breath.
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - Zero
so the masks didn't drop from the headlining then?
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - R.P.
It's a BMW not a Saab..
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - legacylad
I have now done some reading up on oxygen sensors and will contact my local BMW dealer this am. This weekend I plan to drive 300 miles and need reassurance that driving with this warning light on will not cause further damage in the short term.
I believe the sensor 'reads' the fuel/air mix and if incorrect can seriously damage the cat.
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - Dog
>>The cabin oxygen is ok because I could still breath<<

If you had still breath, you'd be brown bread m8.
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - Dave_
Is it petrol or diesel? If diesel, does it have a DPF?

My DPF-equipped Peugeot 406 a few years ago used to come up with a similar message ("antipollution equipment defect" or something) which just meant a regen was needed.

>> I believe the sensor 'reads' the fuel/air mix and if incorrect can seriously damage the cat.

If it's petrol I shouldn't worry about the long drive too much. I had a Toyota Carina E (cat equipped) which spent half its time running on 3 cylinders and the other half being push-started. It burned oil at 1 litre/ 1000 miles too. Passed 2 MoTs like it, emissions were well within limits.

On an 8 year old car I would use pattern parts if needed anyway, a cat won't cost you more than 150 quid: www.cats2u.co.uk/product_info.php?products_id=28775
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - madf
Check for a small leak in the catalyst...

(Any exhaust paste eg Gun Gum) will repair it for months..
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - legacylad
Final update.
First of all, thanks for all your replies and advice.

A friend of mine, who is good at this kind of thing although not a trained mechanic, bought off Ebay a Canscan D900 scanner for £30 to retrieve the fault codes for me.
These were P0174 (system too lean ) & P0598 (thermostat heater control circuit low).

The root cause of P0174 was a split in the air intake tube from the MAF mass airflow sensor to the throttle body. The part was delivered to his door by Lloyds BMW Colne at a total cost of £10.20. Plaudits to them.

P0598 was a worn electrical heater in the thermostat, and the entire thermostat housing was replaced at a cost of £24.80 from BM parts in Sheffield (vs £79.20 from Lloyds BMW). The part needed a ferrule filing down to fit properly as initially there was coolant leakage despite use of blue hylomar.
To do this the rad fan & cowl were disconnected, plus engine undertray. The coolant was changed and pump checked and some hex bolts replaced which had been rounded off.

All too technical for me, so it looks like I shall be mowing his lawns for the next summer in exchange for his efforts!
 BMW 3-Series E90 - 04 3.0 Warning light on. action required? - carmalade
Glad you got it sorted.But I think I would be a little worried about using parts that did not fit properly and ended up using blue gunge to stop it leaking.Probably ok on an old Cortina but not on one of these.No temp gauge on these,If I recall?
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