Technical Replace or delete twinair cat?

[bpalmer]

We've got a 2017 4x4 twinair Cross that has been brilliant for years, even using it as a proper 4x4 with plenty of off road here in South Africa. But recently it's been in and out of the garage and we need some advice as to what to do ...


At the last service about 9 months ago (50 000km) we needed to replace the water pump, frustrating on such a young car but not too crazy expensive. On the way back from a long journey we noticed a slight loss in power/economy and when we stopped at a petrol station to check I noticed a little bit of mayonnaise at the top of the oil cap and got a bit of a fright. I assumed then that the water pump swop had been botched and coolant was getting into the engine.

Long story ... despite being in and out of the dealership a few times ... filling up the coolant a bit since the water pump change, the Fiat dealer insists the engine/coolant system is 100%. They've done dye tests in the coolant as well as compression tests etc. and are adamant that all is well. They say that twinair engines often get a bit of mayo in the filler neck - and we'd just come back from the desert with some extreme highs and lows in temperature which could have caused this.

A few weeks ago we had an orange warning light with the engine light - straight back to the dealer. The dealer said it's the catalytic converter error and cleared it ... apparently nothing to worry about.

The coolant level has since stabilized, but always sits in the middle of the max/min - if you top it up to max level it always goes to the middle after a while - the dealer again says that is normal on these cars.

This weekend the dreaded orange engine light came on again, no loss of power or economy, but back to the dealer again to check. They came back with the cat error again - P0420-62 (signal compare failure). The dealer says they can't delete it as it's showing as 'active' whenever the car is on. The only solution the dealer has put on the table is to replace the whole cat - as it's a sealed unit.

It is crazy expensive to replace the whole cat (£2000 just for the part) - so I'm wondering what out other options are? It's also bonkers to be having this problem at 55000km and only 4 years old.

There are no cat specialists here who can attempt to clean or service it - so do I go to an exhaust specialist and get the cat removed and deleted? Can you clean or replace the sensors on a twinair as a starting point? It just seems odd that it's a full cat replacement or nothing from the dealer?

Any advice as to what to do next or check would be greatly appreciated. Thanks in advance!

 

[The Pretender]

I would choose a Cat delete downpipe.
You could end up with 140 hp with stage 1 software.

 

[mj2k]

I would choose a Cat delete downpipe.
You could end up with 140 hp with stage 1 software.

I've been wondering about cat deletes (albeit on an Abarth 595 rather than a Panda twinair), does removing the cat cause any emissions issues at MOT / TUV (or is yours APK?) time?

 

[The Pretender]

I don’t know.

 

[mj2k]

I don’t know.

Guess that makes two (maybe three) of us then

Must do some more research into that...

As for the OP's issue, I'd take it to another dealer or a well liked and respected 3rd party mechanic if I were you for a second opinion, coolant loss and premature cat failure (esp as there's no way a water leak could cause the cat to fail) don't sound normal to me for any modern car, well unless you've been regularly beating it with a crowbar.

 

[bpalmer]

I've been wondering about cat deletes (albeit on an Abarth 595 rather than a Panda twinair), does removing the cat cause any emissions issues at MOT / TUV (or is yours APK?) time?

We don't have emissions tests here in South Africa (or even an annual MOT). Having said that I know that the twin air is quite a modern engine design and don't want a cat removal to cause other issues down the line.

 

[bpalmer]

Guess that makes two (maybe three) of us then

Must do some more research into that...

As for the OP's issue, I'd take it to another dealer or a well liked and respected 3rd party mechanic if I were you for a second opinion, coolant loss and premature cat failure (esp as there's no way a water leak could cause the cat to fail) don't sound normal to me for any modern car, well unless you've been regularly beating it with a crowbar.

Thanks - it's going off to a trusted independent mechanic today for a check. I'm hoping he'll be able to inspect the lambda sensors in the cat and take a view on the possible next steps.

It's not been given a hard life at all - the mileage is quite low. I do wonder if it had some bad fuel on one of our journeys out of town, but as you say - coolant loss and premature cat failure is a bit concerning.

Will let you know how it goes with the independent.

 

[Goudrons]

You might have an exhaust leak.
This will allow air into the exhaust and mess up the post cat O2 sensor giving you the P0420, which is the code which usually relates to too much O2 detected in the exhaust gases after the Cat.

I'm guessing, but if they have had to strip out the cat/manifold to get at the water pump to replace that, they might have not sealed it all up properly and it's leaking.

 

[jrkitching]

I've been wondering about cat deletes (albeit on an Abarth 595 rather than a Panda twinair), does removing the cat cause any emissions issues at MOT / TUV (or is yours APK?) time?

A visual check for the presence of a catalytic converter is part of the MOT inspection schedule in the UK.


I'd also be surprised if it were possible to meet the HC/NOx limits without a working cat.

From the MOT testers manual:

 

[mj2k]

Thanks - it's going off to a trusted independent mechanic today for a check. I'm hoping he'll be able to inspect the lambda sensors in the cat and take a view on the possible next steps.

It's not been given a hard life at all - the mileage is quite low. I do wonder if it had some bad fuel on one of our journeys out of town, but as you say - coolant loss and premature cat failure is a bit concerning.

Will let you know how it goes with the independent.

Fingers crossed

 

[chris3234]

I would choose a Cat delete downpipe.
You could end up with 140 hp with stage 1 software.

And a car that's not road legal

Edit just seennop is in SA so probably legal over there

 

[mj2k]

A visual check for the presence of a catalytic converter is part of the MOT inspection schedule in the UK.


I'd also be surprised if it were possible to meet the HC/NOx limits without a working cat.

From the MOT testers manual:

I was thinking the same, and of course in European countries where the MOT is based on the TUV, the requirements are even stricter.

But decats do seem to be a popular mod on the Abarth at least in the search for power, maybe people put them back in again at MOT time?

 

[bpalmer]

So my trusted independent said that the cat was shot - he could smell it a mile away and it would definitely need to be replaced or deleted. Not the lambda sensor wipe with an oily rag fix I was hoping for.
He managed to find an aftermarket one - for about £500 fitted, which is still a bit brutal but way better than £2000 from the stealers.
I asked him to have a proper look and try to determine why the cat failed, so we can try and avoid another one in a few years time. Will post here if he comes up with anything interesting.
Thanks again for all the suggestions and advice

 

[mj2k]

Cats are stupidly expensive at the moment, mostly because of the rare metals inside them. In the UK thieves have even started stealing cats from people's cars and leaving the rest of the car standing because they're worth so much money in scrap value!

Definitely worth getting that investigated if he can work it out, if something is poisoning the cat, e.g. if somehow a local garage got leaded petrol or if the car's burning oil it would soon finish off the replacement too.

 

[chris3234]

Cats are stupidly expensive at the moment, mostly because of the rare metals inside them. In the UK thieves have even started stealing cats from people's cars and leaving the rest of the car standing because they're worth so much money in scrap value!

Definitely worth getting that investigated if he can work it out, if something is poisoning the cat, e.g. if somehow a local garage got leaded petrol or if the car's burning oil it would soon finish off the replacement too.

They have allwayy been silly money to buy as a replacement

 

[varesecrazy]

Cats are supposedly a little 'fragile'

Is it a 'manicat' ?
or slung under the vehicle being peppered by debris?

 

[bpalmer]

The car came back with a new cat from the trusted mechanic yesterday, who also showed me the state of the cat that was taken out. It did not look too contaminated ... sooty or black, but was quite broken inside and therefore not doing its job. Obvious now what was causing the engine error - a big pity it was something so major.

I can only guess that our off roading caused it to break up inside, maybe also because it was in a hot desert situation with plenty of heavy road corrugation. High outside temperatures, a hot turbo and a few more bumps than usual?

The mechanic replaced with an aftermarket Magnaflow cat - and the warning lights have all dissipated and all seems well. We have to now decide if the Cross really is the right vehicle, we've loved it to date with it's great fuel economy and off road abilities, hopefully just a bit of bad luck and the new cat will last a lifetime.

Thanks again for all the advice and suggestions

 

[jrkitching]

I can only guess that our off roading caused it to break up inside, maybe also because it was in a hot desert situation with plenty of heavy road corrugation. High outside temperatures, a hot turbo and a few more bumps than usual?

One thing you can do to prolong its life is to regularly inspect all the exhaust mountings. It's common for these to break, perish or (in the UK at least) simply rust away. Once the exhaust starts moving more than is intended, it usually isn't long before bits start fracturing and breaking off.

This is quite frequently reported on UK 1.2 Pandas & 500's; there's a clip on the front pipe which usually rusts through after a few years, allowing the front of the exhaust to flex about, often leading to a cracked manifold.

I'm guessing that in a hot desert situation, perished rubber is more likely than rusted steel, but the end result is the same.