Hi Guys,

I have a bit of a problem, my ford Puma has failed the MOT on emissions, and I am pretty sure it's due to the Lambda Sensor. But, as I found out today, there are 2 sensors - pre-cat and post-cat, so how do I know which one to replace??

Help!!

 

Pre-cat Lambda is used for fueling, post-cat is only used to see if the cat is still working.
So it's the pre-cat.
But there could be dozens of other reasons why the emissions fail.

 

Thanks, that is handy to know!

And I'm 99% sure it's the lambda purely because of the readings I got from the emissions, they point to it being the lambda - the car is about to hit 100k and so it seems about the right lifetime for a lambda (although the car has always had lousy consumption so could have failed long ago!)..

I can post the emissions results if anyone else would like to confirm my suspicions?

Thanks

 

I've lately been using universal lambda's with excellent results, found them on the net, think they were called something along the lines of all lambda, but were around £35 and work perfect.
tabetha

 

Where do you get them from? And can I definitely use them on the 1.7 puma? I am selling the car so only need to get the car through the MOT really, but don't want to spend £35 on something which will then not work!

 

have it put onto IDS and using realtime display it will show which one is the bad one in a matter of mins.

alternativly unplug one, drive car see what happens, then replug and unplug the other one go for drive, which ever one is faulty once unplugged car should go into preset values, had this problem with missus racing puma car kept cutting out and it was the post cat one, once unplugged car ran fine, i did check it with realtime display first before spending any money on it though, new one cost me £70 from eurocar parts