02 sensor readings HELP! please

whatthevec

hi all, right i have a fault code keep appearing which is po420,which i know what that is, as i am using a maxscan obd11 tester, i have noticed that my car lacks a little power [holding back] when i accelarate, not coughing or spluttering or anything like that, just dont seem to go like it should. i have just done some live o2 sensor data using my scanner these are the readings i am getting at 2500rpm when car is at normal running temprature.
o2 bank1 sensor 1 0.065- 0.830v
o2 bank1 sensor 2 0.225- 0.800v

sensor 2 reading dont seem to change as much as sensor 1

could someone please tell me if this looks right or not? or if poss point me in the right direction,

any help would be great, cheers all, Guy....

blue_se2

is ECM light actualy on then?

whatthevec

hi neil, by ecm do you mean eml light? if so yes it keeps coming on, same fault code po420, but i just keep knocking it back out, cheers. Guy.

vocky

bank1 should be the mixture lambda and bank2 the cat is working lambda - which shouldn't alter that much

MikeS

looks to me like your car is running rich and your cat looks worn

your bank 2 sensor should be very static at idle and low revs, only at high revs should it spike above .6 volts

first lambda sensor should not go over .8 volts and should be pulsing every second otherwise it is faulty

at idle at operating temp is should be puling between .2 and .6 volts and the 2nd lambda should be around .2 - .4

Spooks

If it helps, I've had this fault for over a year, i thought it may be the cat so had the emissions tested a week before the MOT and they were fine, and it then sailed throught the MOT. I also had a small leak at the manifold which i've fixed but I still get the same fault code. Next thing I'm gonna try is replacing the pre-sensor but due to moving house next week, the funds are tight so it'll be a while again now. although a sensor is only about £60.

Interested to know how you get on, good luck.

whatthevec

cheers guy's thanks for the info, every little helps, i will have another look, and do some more test, i will let you all know the outcome, thanks, Guy...

Marko

does this link help at all?

http://www.obd-codes.com/p0420

rik1083

it's either faulty cat sensor (sensor 2) or faulty cat. I'd say that because it's passed the MOT fine, then it's a faulty sensor.

Spooks

But the display for fault code P0420 is emissions (bank 1)??? would bank 1 not be the pre sensor then? I think P0430 says bank 2????

rik1083

they are both bank 1 (you don't have a v6/v8 so there is no bank 2)

click on the link
http://www.obd-codes.com/p0420

MikeS

it is bank0 and bank 1