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Emissions - 987.1 S


PCGB Member
My car went in for MOT this week and there was a marginal failure on emissions. I use a well known and reputable specialist for servicing. There were no faults showing there are no running issues.

They suggested 2 options, the oxygen sensors (there are 4 at £100 a go) or the catalysts (2 at £800 odd each).

They persuaded the MOT centre to pass me this year but they won't do it again next.

Do I just need to swallow the £3K to sort it out, or has anyone had the same issue and there was a cheaper solution?
Lob some Cataclean or other suitable fuel treatment in your tank and see how it fares next time.

I had two of my cats removed when Carnewal modified my exhaust and the emissions were actually lower on the MOT than the previous year.
Sometimes it’s just down to an on-the-day measurement Colin and - as James suggests - try using some fuel treatment … or if you’re not already using it, maybe fill up with some premium 98-octane fuel [Esso, Shell, etc.] with plenty of bespoke additives.

Don’t quote me on this but I seem to recall that on the 986 Boxster it was possible to “desensitise” the lambda sensors using the diagnostics, so it may be useful to see if something similar is possible on your 987.1.

I'm using Sainsbury's finest super unleaded!

Don't confuse high octane with fuel additives - as others have said Esso ( zero ethanol) Supreme or Shell 's equivalent will have more "stuff" in it - the Octane rating is about optimium timing and "knock" resistance - the additives are supposed to be the ones that help this kind of thing - along with good and hot and a decent drive before hand.
Aren't all high octane fuels made in the same refinery anyway?
There are certainly fewer refineries than there are brands of petrol stations.

But again. It’s about the additives. Not the octane. And those are not done at the refinery.

I wound imagine it’s similar to ethanol. Whilst Esso is labelled e5 it is (or was until recently) zero ethanol in most of the UK.

That isn’t a “done at refinery” mix - can’t be.

Personally. I believe that over the long term it makes a difference especially to vehicles that sit for longer periods of time (although that’s more ethanol than additives)

For sure. I would take a tank of whatever I could get fuel over walking home. But over the long term I believe that the additives make a difference.

Certainly If I was looking at firing a 3.5k “might be this or might be that” parts cannon at an emissions problem I would start with a couple of tanks of “branded fuel” and a bottle of cat cleaner - might come to 30 quid more than the equivalent supermarket fill ups but also might just tip the fine balance the other way.

But that’s me and the choices I make. It’s always the individuals car, money, choice and satisfaction that matters.
With the club Esso card, the price delta over regular is reduced. Also, check around different Esso (other brands available) outlets for the best price. A local Esso near me is often cheaper before discount than the nearby Tesco for 98 octane. It is also worth remembering that higher ethanol content reduces the energy per litre so going for E5 rather than the cheap E10 stuff should improve mpg, or give a little performance boost when driving like an Italian. Gains are marginal but I'll take whatever I can get.
I had a go with the Cataclean, £17.50 from Halfrauds. I was rather expecting to see white smoke billowing out of the exhaust for a few miles, once the engine was hot, but nothing much happened.

I will give it another go before next year's MOT.
Marginal fail

Would be interested in the MoT data for this, given that it quotes the acceptable ranges for the various criteria

Going forward, you could have emissions checks done at any time to see the possible effectiveness of any treatments etc.

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