Right I made a balls up. I read the fault code thinking it was sensor 1 bank 2 so I replaced the oxygen sensor. (Brought off eBay) got the EML turned off after about 20 miles it’s came back on. I checked the code and it’s the same one so I’ve gone to a ford dealer for the part thinking it’s because I’ve brought a cheaper one off eBay. So I fitted the new part got the light turned off and again after 20ish miles it came back on, so I’ve done some research and I’ve messed up I’ve been changing the wrong sensor it was meant to be bank 1 sensor 2 (post cat) so my question is can I use the spare sensor from eBay to replace the faulty sensor from post cat or do I have to by the sensor meant for post cat? 

Morale of the story is research before you buy 😂 

Thanks for any advice 

What was your diagnostic testing to prove you had a faulty lambda sensor?

 

Yes p0136 is the code

But how did you prove the sensor is at fault? 

Nothing I’m just assuming. EML came on plugged it in came up with that code searched the code and it said lambda sensor fault so just replaced it straight away but replaced the wrong one. So just need to see if my spare lambda will work in the post cat or if I need to buy the corrrect one, since I have a spare I thought I’d see if it could work 

You would need to change the plug/alter the wiring but I can’t see why it wouldn’t work. 

For me I’d want to prove the voltage from the sensor is correct with what the ecu is seeing. That way ruling out any wiring issue. 

I’ll give it a check and see what it says cheers for the advice 👍