Technical Check engine light + P0420

[agoraphobic]

Hello everyone, I'm new here
I hope I'm not dropping a bomb on you, but I'd really appreciate your help with this.

My 2005 Punto is having some troubles lately:
The check engine light has come on and a check I made using the torque application yielded the dreaded P0420.
The funny thing is that I managed to pass the MOT with these conditions with Lambda valued at 1.01 - so my conclusion at that time was that the cat is ok, But there are more problems.

I ran Mode 6 tests and failed TID: $01 CID:$05 "Rich to Lean sensor threshold voltage (constant) Max: 115, Current: 142 which tells me absolutely nothing. I tried researching this on the web but found some information about other manufacturers but not Fiats.

I have been getting some fuel smell around the car and been having bad MPG.
After a look under the hood I didnt find any gas leaks but heard some high hissing sound from the throttle area, but couldn't find the hissing source.

Can the loss of vacuum be the reason for getting the gas smell and bad MPG?
Can it be that be the only fault or maybe there are more faults?
Can someone please explain the results from the test I ran in mode 6?

I love taking care of the car on my own and would love to fix this one on my own too.

Thanks you for your help and reading

 

[s and b]

i had this code 2 weeks ago
co was just out of uk emissions parameter and so failed its mot (licence to be on our roads u
i think mine had suffered a thermal shock
lambdas working fine
no excessive oil burn killing the cat nothing
new s/h cat solved the problem
it was like 0.45 co on fast idle

look here for guidance
http://www.obd-codes.com/p0420

 

[agoraphobic]

No one has other suggestions?

Can someone point me to some information about Mode 6?

I'm sure the reason is something else.

Sent from my Galaxy Nexus using Tapatalk 2

 

[s and b]

mode 6 made my hair fall out
be very careful

 

[agoraphobic]

LOLB-)

I think that this is the socond time you misjudge something in one post

Now really, Can you point me to some information?

 

[s and b]

ive no idea what this mode 6 is thet you speak of
did you read my original post?
did you read the link i provided
as i said in my case the cat had had a thermal shock i guess so even when inspected the matrix looked to be in place but it couldnt catalise as it should so brought up the code
you say you have fumes so i mentioned burning oil? this would kill a cat as it contaminates it and would also give you fumes if they were escaping as the emmision control from the sump failed to keep up,think breather pipe to airbox
have you done a compression test
and a vacuum test would confir whether engine running smooothly