02 sensor/P0420 problem

[H1GRM]

Interesting, so how do you keep the mixture "just so"?

Greg

[thetyrant]

Indeed its behaving exactly like a sport cat but its meant to be oe spec replacement so not sure whether to be happy it might be flowing better than oe, or mad that its not cleaning the exhaust up like oe does and it should be.

[Carolyn]

Hey, they pass inspection.  Once hot, they do the job.

[shnazzle]

Hey, they pass inspection.  Once hot, they do the job.

Yeah but I can see that if he's no bought a oem-like replacement, it's not unreasonable to expect that it performs in the normal cycle. Especially as its quite new.

I'd be keen to send back with some test results and say, look, this one isn't doing what it says on the tin. 
I know it's cheap as chips but still...

[thetyrant]

Hey, they pass inspection.  Once hot, they do the job.

Yeah but I can see that if he's no bought a oem-like replacement, it's not unreasonable to expect that it performs in the normal cycle. Especially as its quite new.

I'd be keen to send back with some test results and say, look, this one isn't doing what it says on the tin.
I know it's cheap as chips but still...

Indeed my thoughts exactly, if i had bought it as a sports cat i would expect this sort of behavior and needing a lot of heat to pass mot etc, but as its meant to be a like for like replacement it shouldnt put the EML on for normal usage. I do wonder if the higher grade certified cat they offer would work better for the extra £30 they charge for it,

Interestingly the info/warranty pamphlet that comes with cat says PO420 is a common issue people see with them and its often not the cats fault, reading between the lines the cats are only just good enough to get the mot pass and any slight issue with car and it will give this code and possible mot fail, if they were £50 i would say fair enough but not at £150 it should work as oem in normal cycles, it could of course just be mine is slightly under spec so causing the problem but im skeptical

Also to add i guess if i still had precat manifold in place doing some gas cleaning then there wouldnt be an issue!

Will see what they say.

[shnazzle]

Aha. I wasn't aware they sold different "grades".
You probably did inadvertently buy a 200 cell.

[Carolyn]

Mine needed the high-idle to get it to conform.... and then settled down  at low idle too. But then, when you're driving, 3,000 rpm under load must be sufficient for the cat to keep working.  Mine, as I said, is now wrapped from the flexis to the cat.  Got to help.  The OEM is heavily heat-shielded, which must help the cat.

Mine will never throw that code' cos I'be told it not too.  (And it's an MR S with no post-cat sensor...)

[thetyrant]

I wonder if I can swap over the heatshield from OEM cat to help keep it hot, rather not wrap it due to location and getting all soggy etc, as mentioned above mine would conform once heated with fast idle but after 5minutes sat idling it went out of spec again which is not good

I guess I could fit a fouler onto rear 02 to stop light coming on just shouldn't have to imo.

[Carolyn]

I wonder if I can swap over the heatshield from OEM cat to help keep it hot, rather not wrap it due to location and getting all soggy etc, as mentioned above mine would conform once heated with fast idle but after 5minutes sat idling it went out of spec again which is not good

I guess I could fit a fouler onto rear 02 to stop light coming on just shouldn't have to imo.

Hard to imagine a hot exhaust 'getting soggy'...

[thetyrant]

Hard to imagine a hot exhaust 'getting soggy'...

You havent been to Lake district then i take it and seen our big puddles  lol   in all seriousness i am a little concerned about the exposed cat with no shielding as we do get a good amount of rain up here, i try not to use the 2 in the rain but cant always be avoided, i dont like exhaust wrap on road cars so might see if oe heatshield can be adapted.

[thetyrant]

Still having the issue and think its getting worse with EML on several times at weekend after a 350mile round trip, ive spoken to Cats2u about it today and i need to submit a warranty claim on the website as 1st step but i cant for life of me find my Order ID/Paperwork arrrgh!  no paperwork came in box with the cat and while i did get email confirmation with my order details at the time of purchase i cant find it typically!, i will have to see if i can turn it up otherwise i cant submit the claim

Best dig out the OE cats i have and see about fixing the flexi's as may need it for mot if we cant get it through with this one fitted!  Annoyed with myself about paperwork as i keep everything as a rule but cant find this anywhere!

Will update as things progress.

[thetyrant]

Found my paperwork and will be getting a warranty claim in when i get a minute, ive so much on at moment ive not had chance and my other car is in for MOT this week then im away on holiday next week,  MR2 needs MOT when im back and im tempted to get him to fail it on cat if it doesnt pass first time before really working it (might have no choice if its got worse) then i have a sheet to send for warranty claim.

I was monitoring the data yesterday when driving after having reset EML and its strange how there is no set pattern to when cat works and doesnt, i might refit the nappy see if the reduced airflow over cat helps keep it hotter but it seems a bit random anyhows and even when sitting at high speeds when cat should be very hot it drops in and out of being active, on sunday i had a fast blast over the a66 sat at a fair old speed as was a bit late setting off, no EML... then ran all day at sprint at Croft with multiple stop/starts and going from cool to very hot over 1 lap, no EML.... set off home at normal steady pace and about 10 minutes into the trip EML came on!, reset it and no further issues with it depsite data showing some non-cat active behavior on lots of the journey, stupid thing!

[Ardent]

Do bear in mind it operates on a 2 trip logic to trigger the eml.

So whatever the circumstances are, they will need to happen back to back on seperate drives.

As I understand it.

[deviantmr-s]

Found my paperwork and will be getting a warranty claim in when i get a minute, ive so much on at moment ive not had chance and my other car is in for MOT this week then im away on holiday next week,  MR2 needs MOT when im back and im tempted to get him to fail it on cat if it doesnt pass first time before really working it (might have no choice if its got worse) then i have a sheet to send for warranty claim.

I was monitoring the data yesterday when driving after having reset EML and its strange how there is no set pattern to when cat works and doesnt, i might refit the nappy see if the reduced airflow over cat helps keep it hotter but it seems a bit random anyhows and even when sitting at high speeds when cat should be very hot it drops in and out of being active, on sunday i had a fast blast over the a66 sat at a fair old speed as was a bit late setting off, no EML... then ran all day at sprint at Croft with multiple stop/starts and going from cool to very hot over 1 lap, no EML.... set off home at normal steady pace and about 10 minutes into the trip EML came on!, reset it and no further issues with it depsite data showing some non-cat active behavior on lots of the journey, stupid thing!

Welcome to my world! Sounds incredibly similar to what has happened to mine. My outlook now is that I am no longer going to get worked up about it.

[thetyrant]

Indeed im the same i guess and forget about it for days then EML comes on again, which does annoy me again!, it will get sorted either before or after the mot but as im planning power upgrades over winter anyhows exhaust is on cards for upgrade to suit, just hoped for no hassles until then hence buying the cats2u unit, never mind we will get there

What are you doing with yours and is the cat pipe custom or just backbox ?

[deviantmr-s]

Indeed im the same i guess and forget about it for days then EML comes on again, which does annoy me again!, it will get sorted either before or after the mot but as im planning power upgrades over winter anyhows exhaust is on cards for upgrade to suit, just hoped for no hassles until then hence buying the cats2u unit, never mind we will get there

What are you doing with yours and is the cat pipe custom or just backbox ?

It will be reverted back to standard shortly. The cat pipe is welded to the backbox as one unit, so the whole lot has to come off. The joys of owning an 2 I guess...
 

[shnazzle]

Might have already asked but are you guys running aftermarket intakes? 
Just asking bevause I always got p0420 with my sports cat, but since I switched back to stock intake, haven't seen it yet

[deviantmr-s]

Might have already asked but are you guys running aftermarket intakes?
Just asking bevause I always got p0420 with my sports cat, but since I switched back to stock intake, haven't seen it yet

No just stock. Interestingly my mechanic friend has reiterated to me that with the manifold, cat and backbox he would expect that code coming up and is not a problem. But that does not explain why some get it and some do not when they change set ups! Just frustrating to say the least.

[thetyrant]

Stock intake here as well, I wonder if yours is just running better now with the stock intake which has been enough to give cat less work to do, probably get the EML next time out now your said that lol

[jonbill]

Are you sure you're not both looking for patterns and meaning where there is none, and your cat has just failed?

[deviantmr-s]

Are you sure you're not both looking for patterns and meaning where there is none, and your cat has just failed?

More than likely for me, reverting back to stock for now.

[shnazzle]

It's quite simple really. 
P0420 is cat efficiency. So, assuming no leaks of any kind, it's either your fueling (e.g. My situation with my aftermarket intake) or your cat.

Your fueling should be OK if:
- stock intake with clean filter
- stock ecu
- correctly working o2 sensors, and not overly aged. 
- working and clean maf
- no leaks (vacuum or exhaust) 
- no excessive oil burning 
- clean, non-leaking and working injectors
- good state of correct spark plugs.
- no blockages in exhaust (pre or main cats) 

The fueling can be verified by TorquePro or the like. If LTFT is around - /+5%, possibly +/- 10%

So if fueling is verified. It's your cat. End of. Your car is doing everything it can to be as efficient and low-emissions as it can,the rest is up to the cat. 

There are aftermarket cats and aftermarket cats. The cheaper, the less expensive precious metal catalytic material. The less material, the less it can convert exhaust to acceptable levels. Spend little, expect p0420, particularly when cruising down the motorway. Expect to have to get it glowing red to pass MOT. If at all. Keep code reader plugged in and clear when it comes up. 

Spend lots, you either get a 400 cell or a 200 with a lot of expensive precious metals that can adequately do the job.

Once you go down the route of 200 or less cells, for the budgets we usually have, you're really best to expect the occasional p0420 at best. 
O2 foulers can provide some relief.

[thetyrant]

Are you sure you're not both looking for patterns and meaning where there is none, and your cat has just failed?

Yes indeed my cat is at fault ive proven that as Ive done all the tests including mot emissions test at garage to confirm intermittent operation, im now just curious as to the logic ECU uses to determine the problem but no logical pattern ive found, it doesnt matter i was just curious

My cat is new with less than thousand miles on it before it started to work intermittently, i did several hundred miles and few long motorway journeys without problems then it just fired up the EML about a month after fitting it, no doubt some issue with quality as it should last a bit longer that that i feel, i dont expect it to last 14years like the OEM one did before flexi failed (cat itself still working just the flexi failed) but do expect it to last longer than it has, no doubt i will have to return it for inspection so interested to see what they say.

 

[jonbill]

Fwiw, I've got two cars with cats2u cats - both have done about 15k miles without problems.
Neither of us are statistically significant, but I expect many on here use them and we don't hear a lot of problems, so I hope you've been unlucky and maybe they'll sort you out with a warranty replacement.

[thetyrant]

Good to hear you had decent life from them so there is hope

Refitted the nappy last night and only had a 10 mile or so testdrive but data from the post cat 02 sensor certainly looked more stable so the extra heat from having cat partly shielded by nappy seems to help, I couldn't believe how hot engine bay was when I got back and I wasn't thrashing it!   I removed nappy just after car purchase to sort a few jobs and service etc so not had much experience running with it to compare, certainly seems to make it hotter under the hood with it fitted though.