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Hello all

my 57plate IS250 failed MOT on its emissions. 
CO emissions 1.62% but the limit is 0.2%
 

lambda emission is 0.95 but limit is 0.97to1.05

The diagnostic was run and there is t any electrical sensor fault and there isn’t any warning light on in the dashboard. 
The garage has suggested to go for terraclean which will hopefully clear the carbon buildups and result in a lower emission. 
 

Could it be the case?

Mileage is 99k. 
 

any helpful information be appreciated. 
 

thank you

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have you ever had to change the O2 sensors? 99k miles and 13 years old, they might not be reading 100% which could result in higher than normal CO.

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1 hour ago, Brechin Slate said:

Hi Harpreet, petrol or diesel?

The IS250 is a petrol V6 engine, the only diesels Lexus every made were the IS220d and IS200d.

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Has it been serviced regularly particularly the air filter and oil.

How is the car used, just around town or longer higher speed journeys, a good run can do wonders on a town dwelling car.

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27 minutes ago, steve2006 said:

The IS250 is a petrol V6 engine, the only diesels Lexus every made were the IS220d and IS200d.

Whoops, need to wear my glasses!

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50 minutes ago, ColinBarber said:

have you ever had to change the O2 sensors? 99k miles and 13 years old, they might not be reading 100% which could result in higher than normal CO.

Hello

never changed it. But if it’s faulty, would it not show up in diagnostic process?

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33 minutes ago, steve2006 said:

Has it been serviced regularly particularly the air filter and oil.

How is the car used, just around town or longer higher speed journeys, a good run can do wonders on a town dwelling car.

Yes

it was last serviced in September 2019 by Lexus, oil and filter service

since March 2020, it has only been used about 500 miles and mainly short journeys like 3 4 miles. 

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33 minutes ago, Harpreet said:

Hello

never changed it. But if it’s faulty, would it not show up in diagnostic process?

Not always, it has to be really bad for an error to be detected.

I'd start with cleaning your MAF sensor as that is a simple thing to do.

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I have done terraclean - car was ~160k miles at the time... as a matter of fact I don't even know why I did it... probably as preventative maintenance and hoping that engine will be more efficient or something. The test sheet showed 0.00% emissions before the clean and 0.00% emissions after the test... seems like I was running on hydrogen all the time.

In short, it made no difference on my car, but I didn't have problem in the first place. So who knows... apart of that I didn't felt any improvements after terraclean whatsoever.

As somebody already suggested, considering that car was driven rarely and for short journeys simply blasting it for 20 min on motorway and getting fully warmed-up before MOT could be all it needs.

If at all possible I always try to do MOT right after driving when car is still warm, some more reasonable places as well runs the engine at least for few minutes before testing emissions, because to be fair any ICE car would fail the test if they put the probe on cold engine and only then started the it.

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I think you are going to suffer other issues long before you emissions go high due to carbon build up. Poor acceleration, poor starting, poor idle etc.

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15 minutes ago, ColinBarber said:

Not always, it has to be really bad for an error to be detected.

I'd start with cleaning your MAF sensor as that is a simple thing to do.

Please can you direct me in the right direction on how to clean the MAF sensor?

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13 minutes ago, Linas.P said:

I have done terraclean - car was ~160k miles at the time... as a matter of fact I don't even know why I did it... probably as preventative maintenance and hoping that engine will be more efficient or something. The test sheet showed 0.00% emissions before the clean and 0.00% emissions after the test... seems like I was running on hydrogen all the time.

In short, it made no difference on my car, but I didn't have problem in the first place. So who knows... apart of that I didn't felt any improvements after terraclean whatsoever.

As somebody already suggested, considering that car was driven rarely and for short journeys simply blasting it for 20 min on motorway and getting fully warmed-up before MOT could be all it needs.

If at all possible I always try to do MOT right after driving when car is still warm, some more reasonable places as well runs the engine at least for few minutes before testing emissions, because to be fair any ICE car would fail the test if they put the probe on cold engine and only then started the it.

I have someone coming to do a terraclean tomorrow at discounted price (£50). Think will get it done and then go for a 30 min run before going to retest on Monday. But the thing is once I take the car back to garage, there isn’t any guaranty that they will test it then and there.  
I did ask the garage if they tested it on a warmed up car and they said yes. But I know it may not be right. 
I will clean the MAF as well before the retest. 
if needing to replace the o2 sensors, please can you send a link to buy this one. Hope I won’t need it

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That is very cheap for terraclean, must be COVID pricing... before you could not get it done for less than ~£100-£120. At very least it would not hurt. 

You can try to be a little cheeky and try to figure out when they actually going to test it and arrive like 20 min before that. But I do know exactly what you mean... some places just say bring the car in for 9AM and pick-up at 2PM... most of the time when you arrive at 2... only then they say... "ohh yes that car let's do the MOT". 

At some point I found the place which actually gives proper appointments and you out of there within 45 min... 

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19 minutes ago, Linas.P said:

That is very cheap for terraclean, must be COVID pricing... before you could not get it done for less than ~£100-£120. At very least it would not hurt. 

You can try to be a little cheeky and try to figure out when they actually going to test it and arrive like 20 min before that. But I do know exactly what you mean... some places just say bring the car in for 9AM and pick-up at 2PM... most of the time when you arrive at 2... only then they say... "ohh yes that car let's do the MOT". 

At some point I found the place which actually gives proper appointments and you out of there within 45 min... 

yes that’s what I thought to get it done. 
I will post the retest result on Monday. Fingers crossed. 

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Good news

it passed the MOT

CO emission is 0.02% as against 0.2 % limit

lambda within the limits as well. 
 

Honestly speaking the car feels different as well. Very very quiet and acceleration is noticeably better. 
 

just did the terraclean and nothing else. 
 

thanks for all the input

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Good result, thank you for posting the update.

Just out of interest I know you said it was just the Terraclean but did you give it some revs driving it there and back?

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Hi Steve

yes I did run it in 3rd gear for about 10 15 minutes. I made sure that it’s upto the temperature before I dropped off it at mechanics. But he tested it 4 hours later. 
 

when I said it was 0.02 CO, it’s when it’s idle. When it’s tested at 2500rpm, it’s actually 0

thanks scudeny as well for the message. 

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