Why does the engine need both pre and post cat O2 sensors? AFAIK the pre ones talk to the ecu and help keep the air/fuel ratio in check, what are the after cat ones for then?
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Why does the engine need both pre and post cat O2 sensors? AFAIK the pre ones talk to the ecu and help keep the air/fuel ratio in check, what are the after cat ones for then?
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The front two monitor the AFR for the DME and the rears monitor the CATS.
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What do you think of the notion that they should be changed at 100k?
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Mine were gone at 80.
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If I remember correctly I got bosch sensors for an m3 at an okish price from euro car parts. I would imagine they would be the same sensor. Plenty of crud on the old ones so I could see why new ones would be a benefit.
I did the same, bought Bosch units on amazon for mine and they were a fraction of the price of OE
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Notice much of a difference after?
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Just a smoother and cleaner power delivery, emissions were much better too.
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Had you lights on the dash before?
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No, but it failed the NCT and the readings seemed out on INPA
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Hmm
I must plug in again. And check out the readings. I don't mind buying 4 sensors, but don't want to throw them at it for the sake of it. The only fault / dtc was O2 sensor after cat, bank 1, voltage monitoring.
But if it was to drive better I'd get them. It seems to have a fair old smell of fumes on startup, but I still get 22 mpg cruising.
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I get close to 30 on a gentle cruise
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Is that after zeroing the counter once you're cruising?Quote:
Originally Posted by Dave
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http://uploads.tapatalk-cdn.com/2016...074e7620d3.jpg
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http://www.transportsupplies.co.uk/i...5_580mm/11924/
Seems very cheap.
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I fitted 2 of those, genuine Bosch and worked perfectly.
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ecuworx do software for turning off 2nd set of sensors for the e46. I think it works for the e39 too, mostly done when removing the cats.
Its like £20 for the licence and you can make other changes too.
Have you noticed any difference? I've just bought two pre cat ones for my M3 as it's on 106k miles
That's a great little program. I used it to change a good few things. It does work for the e39 as well alright.Quote:
Originally Posted by Smokey Bear
So if the post cat sensors were throwing up errors could you just deactivate them? Even if you weren't removing the cats?
I fitted 2 of those, genuine Bosch and worked perfectly.
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I haven't driven it much tbh. But the DTC is now staying gone. I'm going to change the pre cat ones in a week or so. Just to keep it tip top.Quote:
Originally Posted by doyleeoin
I'd be more interested in turning off the Auxiliary air pump than any of the lambda features tbh.
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Its the pre-cat ones I'd would have changed first TBH. They're not that expensive anyway I suppose.
One of the post cats was faulty. Hence being changed first.Quote:
Originally Posted by Smokey Bear
Pre cats will be changed purely as a preemptive measure.
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