Mot Failed

newport · January 28, 2015

My RX300 Mk 1 02 has failed the mot ... CO levels too high Fast Idle Test..Actual value 0.766 Max Limit 0.300. Second Fast Idle test.. Actual Value 0.530 Max Limit 0.300. she passed on everything else.

The guys say "Needs new Cats Mate" ... they seen sure its not sensors.

I can get Catalytic converters for this car front and back from the USA for £365 with post and customs.

Is this a good price as here in the UK they are alot more and is there only two cats or is there a 3rd.

Any help anyone can give on this would be nice.....I dont have any engine check lights on and she drives very nice.

Thanks guys.

nelmo · January 28, 2015

Who's the 'guy'? Lexus dealer or back street hacker? Personally, I'd get a second opinion as I've never heard of anyone neeeding new cats - I thought they were supposed to last for the life of the car?

ChrisIS200SportTTE · January 28, 2015

I'd also get an emissions test done elsewhere to confirm it failed emissions

ChrisIS200SportTTE · January 28, 2015

Because the car is running fine with no warning lights it shouldn't fail emissions. If cats were goosed you'd have running problems and the engine management light giving CAT codes

newport · January 28, 2015

Thanks Guys for your input, and I agree with you all, It is my local car repair man who I have known for along time, and he uses our local mot station he says the sensors are switching ok and it can only be the cats or a cat, but yes I agree strange no error lights so no codes, and it is only the CO levels HC is ok and yes I will get a second test done before i do anything,

I will let you know what they find.

Thanks

jonthebarber · January 29, 2015

Hi

Long shot , what about running a bottle of engine cleaner , say whynns etc , fill her with full fat fuel (shell opitmax , for example) and give it a good blast before re-test ?

Jon

newport · January 29, 2015

Good idea may come to that.. Im having a e test tomorrow from another station only costs a £10 ill let you know.

jonthebarber · January 29, 2015

Good luck 👍

Jon

ColinBarber · January 29, 2015

It could be that the upstream air/fuel ratio sensors are on their way out and running the engine slightly rich, which would increase CO levels. Have your upstream sensors been replaced recently - they don't tend to last more than 10 years so I'd be surprised if you are still on the original ones.

Otherwise yes the cats are probably in need of a replacement. The downstream oxygen sensor is meant to check for cat efficiency but it is certainly possible that the cat will fail an emissions test before the check engine light comes on.

doro708 · January 29, 2015

I had a similar issues on my girlfriends Vauxhall astra and everyone told me i need a new cat. 2 bottles of Cataclean from Halfords or Eurocarpats whichever is easier for you and the mot passed without absolutely no problem. It only cost £15-£20 and it might save you rather than buy new cats.

CJHYBRID · January 29, 2015

On one of my previous cars I used a liquid called Cataclean (Google It) which can clean some of the deposits in the Cat and reduce emmisions.

Have a read think Halfords sell it and Europarts might just do the trick

Good Luck

Chris

newport · January 30, 2015

Thanks Guys, Just had another test done at another station and the result is the same well almost, CO levels too high about twice the max limit.

I have been thinking about what CollinBarber said "he is often right", about the MAF sensor Ive cleaned it twice, when the first test failed, it failed on "Natural idle test" CO 0.674 limit 0.500 .. I cleaned the MAF and had it tested again Now it passes the Natural idle test CO down to 0.213 but still fails on the first and second fast idle test still high CO.

Im thinking about replaceing the MAF sensor eBay have them for £26 (after market ones) to see if that changes anything.

The Cataclean might work if the CO levels were just over the max limit but mine is 2x the limit.

Thanks guys for your valued input.

ColinBarber · January 30, 2015

I'd be more inclined to think it is the air/fuel ratio sensors (Oxygen sensors) rather than the MAF, I doubt you would see much improvement compared to your cleaned MAF.

Is your air filter clean?

steve2006 · January 30, 2015

Just out of curiosity if you rev and hold the engine around 2500-3000 RPM is there an rythmic droning noise present which cycles on and off?

newport · January 31, 2015

It has a new air filter and the sensors have been changed at
some point, I spoke to my mechanic he
says the sensors have tested ok he says if after the cats have been changed and
it turns out to be a sensor he will sort that for free, cant ask for better
than that.

So Monday I will order the cats from the states.

http://www.ebay.co.uk/itm/Catalytic-Converter-Direct-Fit-Rear-Y-Pipe-New-For-Lexus-RX300-Toyota-Highlander-/191495428659?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c96045a33#vi-ilComp

ColinBarber · January 31, 2015

The problem with the air/fuel ratio sensors is that they can test ok, in that they respond quickly to rich/lean conditions in a relative way but their actually reading can go off a little - unless you put in a new sensor to compare results it can be difficult to be 100% confident.

I'm sure your existing cats are less efficient than the new ones will be so it will improve or fix the issue, best of luck :)

ampr · January 31, 2015

hi try a bottle cataclean in the fuel for a week then retest £15.99 from Halfords worth a try

Parrot of Doom · February 3, 2015

I had the MOT done on my 400h yesterday and was thinking about this thread. The MOT tester didn't do an emissions test though, after all, how do you force the 400h's engine to run?

Passed with flying colours btw.

newport · February 3, 2015

Sunday I was near Halfords and thought Cataclean as people on here have said its worth a try, so I had a 1/4 tank payed the £15.99 put it in and drove 20 miles and then some more Monday and the car seems a bit better.

Today Tue went to the test station for a em test ........**** **** ***** still the same **** *** but yes worth a try

Just ordered two cats from the states £375 inc plus £60 to fit.

Thanks guys for all your help, I do like this RX the ride is better than my old GS,s mk1 and mk2 even the seats are softer.

thanks all.

doro708 · February 3, 2015

Hi Phil,

Sorry to hear that the Cataclean didn't worked. I have used 2 bottles on half a tank with a vauxhall astra and went o a bit longer journey with the revs a bit higher and it worked. I am curious if the emission values have changed a bit from the Cataclean or they stayed the same. Also have you noticed any economy or performance drop since you have the issue with the catalysts?

newport · February 4, 2015

The CO levels were the same but the car runs that little bit better so Cataclean was worth the money, The guy at the test station said he see alot of this Cataclean dose work for alot of people and not with others its all down to the fault he said he has changed Cats that have a small hole inside so some gases are by passing the cat, Cataclean cannot fix that... Em makes sence.

The car does run very nice, the new cats are on there way.

gkkes · November 7, 2015

Looking at an rx300 on ebuygum based in Taunton which has exactly this problem. MOT fail on emissions.

Gliderpilot · November 8, 2015

Hybrids don't require an emissions test acording to the DVLA

newport · November 9, 2015

The Cats dont last forever, THE CAR WILL... but the cats dont , mine is fine now just coming up to 140,000 miles and drives like new.

ChrisKaye · November 13, 2015

That reminds me, I should clean my mass air flow sensor!

Another thing for the list!

If the cat is a marginal fail, I'd check/change the air filter and clean the mass air flow sensor to see if that helps (usually does).

The next step would be to inspect EGR and maybe PCV valves and clean any gunge out.

If you have access to an OBD tool, you can diagnose cat and O2 sensor problems by watching the readings live with the engine running, if all else fails, then new cat!

Chris.