Post Cat Lambda for De-Cat Car

[S3KL]

Hi guys,

My post-cat lambda sensor has failed, and is bringing up an EML, but I've heard that on decat cars the post cat lambda is pretty useless anyway, so is it worth paying out for a genuine OEM lambda, or am I better off going for a cheapy replacement and hoping for the best??

Cheers

S3KL

 

[<tuffty/>]

whats the fault code?

<tuffty/>

 

[S3KL]

Not got the exact code, but I've been advised by the garage that there is no signal coming from the sensor at all

 

[<tuffty/>]

Car mapped? post cat lambda coded out?

<tuffty/>

 

[S3KL]

Car was remapped at AMD tuning (before my ownership) but I'm not sure if the lambda is coded out or not

 

[<tuffty/>]

EML will come up on a decatted car if not coded out... this is why knowing the fault code is useful... if its the efficiency (or lack of) code then thats a case of having it coded out in the map... the other code that is is typical is the heater which can fault... that 'can' be coded out too...

For reference the post cat lambdas job is to monitor efficiency of the cat... if you are decat then its efficiency is well... none... this is why EML's come on...

To answer your original question you could try getting a cheap secondhand one but seems pointless buying any new one for it especially without knowing what the actual reason for the EML is...

If you can get the actual code and it turns out to be the efficiency one then an alternative could be to try one of these lambda spacers... some say they work although never used one personally

<tuffty/>

 

[S3_Mitch]

Car mapped? post cat lambda coded out?

<tuffty/>

Just out of interest, when I had my exhaust fitted (stage1 AMD btw) we put in a single 200 cell sports CAT and temporarily didn't re-fit the lamda till the following day due to time constraints. Anyhow, despite not having the lamda connected I had no EML come on.. has it likely been coded out? Or possibly faulty? VCDS brings up nothing (except imtermittent running lean code on fuel trim 1 or something) I have just always wondered. BTW still trying to get to the bottom of the lean code but I have bigger issues .. sorry to hi-jack the post

 

[<tuffty/>]

Sounds coded out... lean code could be from a split pipe or potentially a weak fuel pump... would need to log in VCDS to confirm

<tuffty/>

 

[S3_NDJ]

Im about to decat mine next month my car is the APY 2000 with the digital clocks so one of the latest Apy's... if my EML light does come on when u say u get it coded out is this using VCDS or remapping software ? If so i had my car stage 1 mapped at B5 would i have to drive to gloustershire again just to get this coded out or can my garage do it who have VCDS and do remap cars also ????( They have a fair amount of knowledge) dont wanna spend stupid money on fuel just to have the EML coded out lol !!!.... also sorry to jump on this post

 

[<tuffty/>]

Bill may well have already coded it out... not sure what your local garage uses to map with but reading out the map and coding it could corrupt the map if not careful..

Needs coding in the map... VCDS won't touch it

<tuffty/>

 

[S3_NDJ]

Ok thanks Tuffty Fingers Crossed He Has Coded It Out If Not And It Comes On Looks Like A Road Trip Again !!!!
Already Skint Could Do With Saving The Fuel

 

[ayfreetee]

If that skint, put the cat back on until funds allow you to get it sorted.

 

[A3-Lee]

Or buy a lambda spacer for the post cat lambda you will need the 90 degree one to clear the tunnel search lambda spacer on eBay they work

 

[SamHendry]

My APY doesn't have a post cat lamda and I was under the impression none of them have, so how would the ecu ever know you've decat'd.?

 

[A3-Lee]

If it has no post cat lambda the ecu won't ever know

 

[S3_NDJ]

Im pretty sure mine does have a Post CAT lambda however if it doesnt obviously ill be Smilling Ill have a look later on ...however if not ill slap the decat on and if it bugs me enough ill either wait until the month after and drive to see Bill or ill pop the CAT back on... Thanks anyway