2008 MK6 1.25 Fiesta…….I recently got an engine management light on the dash and after plugging it into a diagnostics device found out it was the pre Cat O2 lambada sensor. 
 

Easy I thought, ordered a new one and changed it over, reset the warning and fantastic.
 

EXCEPT now it’s not performing anywhere near what it was previously. A tank would normally show 450 miles and not be too far off that now it shows 360 and struggles to get to that.

I reckon that it’s either (1) it needs to be reprogrammed after a new lambada or (2) the sensor, while working, isn’t that good and I may need a new one (I did get a cheapo one originally). Thoughts and advice?? Thanks all. 
 

 

Can't be reprogrammed.  You're probably right about it being a cheap sensor.

Was it branded at all? 

And was it one where you have to solder the plug on?  Poor connection is a possibility if so.

Could be because it's a cheapie, though I recall other threads where members have bought on fleabay etc and they've been fine. Maybe it's a matter of luck.

Poor connections have also cropped up a few times.

Any other issues apart from fuel consumption? Erratic tickover, etc.

And finally - someone was going to do this - could be due to using a saucy Brazilian dance rather than a proper lambda sensor!😃

16 hours ago, Eric Bloodaxe said:

Could be because it's a cheapie, though I recall other threads where members have bought on fleabay etc and they've been fine. Maybe it's a matter of luck.

Poor connections have also cropped up a few times.

Any other issues apart from fuel consumption? Erratic tickover, etc.

And finally - someone was going to do this - could be due to using a saucy Brazilian dance rather than a proper lambda sensor!😃

🤣🤣 so I wish on the Brazilian dancers.  
 

it was off Amazon so as you said pot luck. No other issues with it at all and no other warning lights. Just ordered another from EuroCar parts so hopefully I’ll get it sorted.