Has My Cat Or O2 Sensor Had It ?

[A3 T]

I did a routine vagcom scan today and the only fault it had was this one:


1 Fault Found:
16804 - Catalyst System: Bank 1: Efficiency Below Threshold
P0420 - 35-10 - - - Intermittent
Readiness: 0000 0000

I've had this fault pop up every now and then but should i be investigating it?

The car has just had its mot and flew through the emissions test.

 

[<tuffty/>]

16804/P0420/001056 - Ross-Tech Wiki

Could be the cat... blowing exhaust (air leaking in) or the sensor... although the sensors tend to throw their own codes...

<tuffty/>

 

[A3 T]

Thanks for the reply mate

Could it be that I'm doing the scan while the engine (cat) was cold?

Do you know where on the exhaust the o2 sensor is?

 

[<tuffty/>]

ECU takes into account the engine is cold... will throw the code if it fails once engine has reached temperature... cat O2 sensor is just past the cat (under the car)

<tuffty/>

 

[A3 T]

Is there anything i can log with vagcom that would determine if its the cat or the o2 sensor ?

I am leaning towards the o2 sensor as the car feels like its holding back a bit when warm and i don't think my fuel economy is the best

 

[A3 T]

Anyone ?

 

[camscockle20vT]

Have u got a cracked manifold by any chance?

 

[A3 T]

Have u got a cracked manifold by any chance?

I hope not

It looks ok, is there anywhere on it that most likely to crack ?

 

[camscockle20vT]

Well i hope its not that for you aswel mate lol i have a hair line fracture that iv not laid eyes on yet, but i can hear the ****** thing, you would also hear like a leaking exhaust kind of noise on boost that should go away when the cars been thrashed if youv got a cracked mani, i only suggest this as it threw up that very code and my o2 sensor is fine!

 

[A3 T]

Well i hope its not that for you aswel mate lol i have a hair line fracture that iv not laid eyes on yet, but i can hear the ****** thing, you would also hear like a leaking exhaust kind of noise on boost that should go away when the cars been thrashed if youv got a cracked mani, i only suggest this as it threw up that very code and my o2 sensor is fine!

It cant be that then mate as I'm sure i would have heard it.

I'm funny with sounds in the car, i even make a point of turning the stereo off and listening out for them (sad i know)....lol

 

[A3 T]

Is there anything i can log with vagcom that would determine if its the cat or the o2 sensor ?

I am leaning towards the o2 sensor as the car feels like its holding back a bit when warm and i don't think my fuel economy is the best

I take it theres nothing i can log

 

[A3 T]

I just did another scan and its not showing any faults what so ever so it looks to be intermittent.


Do you think i need to do anything ?