Hi there

new to this, I have owned a fiesta (not sure what mk it's 52 plate) for 6 months and have done a lot to it. It has 116k miles on clock. I have replaced a lot such as steering rack, Cambelt, clutch etc. My EML light has been on for months.

 

done a diagnostic on it, says catalyst efficiency below threshold bank 1- intermittent. What does this mean it's driving me nuts? Where is the bank 1 sensor on the manifold or by the cat? 

Would appreciate the help

thanks

bank 1 sensor 1 is the uptream lambda on manifold, bank1 sensor2 is after cat, if you have cat efficiency fault then its probaby either sensor 2 , wiring of sensor 2, or cat is faulty.

monitoring of live data on both sensors can pinpoint the issue usually

So bank 1 is under hood at top of manifold? Not under the car. Failed on emissions need to sort it

Oh and it didn't say nothing bout sensor just says bank 1

26 minutes ago, iantt said:

bank 1 sensor 1 is the uptream lambda on manifold, bank1 sensor2 is after cat, if you have cat efficiency fault then its probaby either sensor 2 , wiring of sensor 2, or cat is faulty.

Didn't say anything bout sensor just below threshold bank 1

Bank 1 sensor 2 is air temp isn't it different code to bank 1 sensor 1 that is p0420. Just want to know if sensor on top of manifold is bank 1

there is bank 1 only as its not a v6,v8 etc then there would be a bank 2, so ignore bank 1 , its sensor 1 or sensor 2,

so basically from the info you have its saying the cat efficiently is not working correctly , but intermitantly.

therefore you need to know why, could be catalyst not secure in exhaust allowing gasses to bypass,therefore sensor 2 is picking up that,

or cat could be worn out,

or sensor 2 could be not working as it should giving false readings but within its perrameters.

my guess is its the cat needs replacing without seeing any live data.

and just to clarify , bank 1 sensor 2 is not air temp.

what codes do you have ? just the one?

Yes just the 1 I have readings of the mot emissions test will that help?

I have also had the light turned off it hasn't come on and I have drove 20 miles it's just knowing the problem may still be there is why I want to sort it. If it was the cat it would of come straight back on right?

it would come back on, maybe not straight away , but after a couple of drive cycles it would.

it would start off as a pending code until it triggers the fault a few times, then light will come on.

as i have said previously a live data readings of the 2 sensors will determine the fault, sensor 1 should ocilate rich/lean and sensor 2 should be a steady line when cat is ok, if sensor 2 ocilates then cat not working.

Better to try the sensor first tho correct?

i would get it diagnosed rather than spend money on a sensor guessing.

What would these readings say, looks to me it's only a tiny bit over limit and went down on 2nd fast test so cat must be working? MOT man gave me no ideas was arrogant 

does your code reader not do live data? download the free torque app on phone or tablet and a£3 bluetooth adapter and do data reads of the 2 sensors

What would you say about the picture I sent? I have had it diagnosed hence with code p0420

Where can I get 1 from do you have a link please?

That 1? 

Get an ODB2 plug in reader Bluetooth it yes? I do this asap

Ian I'm sorry I've gone on about it just want to know my mot is due retest soon in 10 days. If I get the readings, would you be able to tell 100% what the problem would be or at least a very good idea of it? I'll get them done and respond thanks I let you know I'm couple of days

from those readings i would unfortunatly say the cat is not working very well, maybe the co is only just over but the hc is alot higher than i would normaly expect even though it passed .

the lambda reading is nearly spot on so manifold sensor1 is working fine.