Another Emissions Light!!!

S

seanodwyer

Member
 Wexford
Seems my Zed just loves turning on the emissions light! Had the O2 sensor in front of the cat replaced two months ago and now the emissions light is back on again. Happened last night on the way home, dropped into third to over take and came on. So frustrating! I hope this is not a sign of problematic things to come.
 
Are you sure you changed the right one in the first place? Its often complicated to determine the correct one to replace! Is/was the car running rich?

Your best bet is to get the codes read off :)
 
OK, just got the codes read again by my local dealer. 14 errors on the front O2 sensor (the one that was replaced three months ago) and 7 errors from the CAT. Mechanic says it looks like the cat is going. Is this common or am I just unlucky? Still have three months on my warranty from the garage where I purchased the car. Are likely to be any difficulties in getting them to do the repair under warranty?
 
After my last post the dealer said to leave it as see what happens. Emissions light came on again last night!!!!!!!!!!!!!! I cannot believe this, surely this is pointing to a broken cat at this stage. Has anyone experieced as many emmision lights as me, or am I just unlucky? :cry:
 
I feel for you mate, that's severe bad luck. Don't hold out much hope that the warranty will help you. Good luck! Things like this spoil the real enjoyment of a car like the z4.
 
I would change both sensors. As EdButler pointed out, its very difficult to know which sensor is faulty, if the first one mis-reads, it will adjust the mixture, which may throw off the second. Also if you run round with a dodgy sensor for too long, the excess fuel can kill a CAT. In normal circumstances a CAT should be for for 80-90K. How many miles has your car done ?

14 errors on the front O2 sensor (the one that was replaced three months ago) and 7 errors from the CAT
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I wasn't aware the CAT had a sensor - I thought thats why there was an O2 sensor before and after the CAT to report on how it was performing. I'm no mechanic so maybe someone can enlighten me or back me up that your being fed a line ?
 
I think you could be right. When I first got the error codes read in June last year myself by an Independent he told me that both were showing errors. However, the BMW garage chose to only replace the first one. Now what I suspect is after happening is what you suggest, the CAT has been damaged. I've only got 60K miles on the car.
 
I would get your emissions checked - MOT Station might do it for you - I suspect even with iffy O2 sensors it would still pass if the CAT was OK ( anyone else verify this ? ) ? I would still bet on replacing both your O2 sensors ( about £50 a pop i think ), as opposed to £500 odd for a CAT.

I didn't see which engine you had - but i seem to remember reading the Z4M's tend to eat O2 sensors for breakfast.......
 
Only a puny 2L :-( Road tax over here is crazy! €1566 a year on an ///M!!!! I'm still hoping the garage will sort this for me under the warranty :-)
 
Ok I got the car back today. The garage replaced the cat and an o2 sensor under warrantee. They even gave me a brand new 3 series diesel to use while they were doing the work. Loved the 3 series, very comfortable and economical. Did highlight how fidgety the steering is on the Z. Presume most of the fault lies with the runflats.
 
Glad you got it sorted. I'm amazed they changed the CAT, but nice that its under warranty.

Did highlight how fidgety the steering is on the Z. Presume most of the fault lies with the runflats.
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I'm not running runflat's, and regularly drive a 5 series for comparison, I don't find the Z fidgety at all, it seems to find the grip and let me feel the road MUCH better than the 5. What brand tyres are you using and how new are they ? the only time i found it a little "loose" was when I was "scrubbing" in the new tyres....
 
They are Dunlop, came new with the car nearly a year ago. It's just the steering wheel reminds me of a game console steering wheel in the way it feels. Hard to explain.
 
OK, orange emissions light came on again last week. Remember I had the Cat replaced only three months ago! Anyway decided to read the codes myself. I got the following:

2CA2 - O2 sensor heater circuit (bank 1, sensor 1) Fault during overrun.
2C46 - O2 sensor (bank 2 sensor 1) signal improbable.

I did have an Ebay sourced K&N air filter in during this period (gone back to standard now), could this have been causing these faults?
 
Got pre cat O2 sensor replaced last week and the bloody light has juts come on again!!!!!!! how one make of car have so many issues with O2 sensors?
 
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