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fusionfan, June 23, 2017 in Ford Fusion Club
upstream or downstream?
Is it bringing up the EML, and does the car have any other symptoms?
I presume you'd start getting a fault code intermittently if it was failing.
I recently just had one replaced on my car and it failed completely and brought up a fault code.
That image looks like a perfect wave form to me :D
if thats upstream then its fine, downstream then cat is knackered.
On 23/06/2017 at 7:02 PM, fusionfan said:
Like Ian & James say, if it is upstream, then I think it looks ok.
The fuel/air mix in a petrol car is continuously varied between a little rich, and a little lean. This enables the cat to reduce the NOx (that means removing oxygen) when rich, and to oxidise CO & unburnt fuel (by adding oxygen), when lean. The design of the cat combined with this swing means it can do both jobs at the same time.
The downstream sensor should have a more stable signal, showing the cat has done its job.
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