SANTI

I have just be told that my MY99 UK Turbo has failed the MOT on emissions.

It passed the idle test completely but failed the lambda part only of the test conducted at 2500 rpm. All other readings were OK. Its on the std exhaust.
(Actual reading 1.05 against accepatable range 0.97 - 1.03 I am told.)

I have had a quick search around but can not see anything that matches these results on previous threads so does anyone know what is causing this? The garage do not want to suggest anything and admit to having little experience of Subarus. (Why did I take it there I hear you ask?)

Is it as simple as it sounds - the lambda sensor?

It may be relevant to add that a new MAF was fitted about six week ago & I have not been aware of any obvious idle/pick-up/other faults.

Any help graetly appreciated as the car is still at the MOT station so with a bit of direction I may get it through today.

J.

MrDBM

is the car on it's original lamda sensor?

If so then it's probably given up, have you had any unexplained Check Engines Lights lately?

Mine gave up last year, just scraped the MoT - tester tried again a couple of times. You'll probably find that fitting a new ones solves the problem pretty quickly. I can't remember how much they are from the dealer, although please shop around, the differences are astounding. you can get non OEM ones for around £40 IIRC.

Not wanting to tempt fate, but if you're on your original MAF as well as 02, I would stick a bit of money away for one of those too...

SANTI

Thanks for that.
No CEL at all lately. In fact everything normal I thought.
You are right about prices varying. On the Web £32 incl, locally £45 - £55 + VAT.

Just worried in case I order it & it still won't pass! Someone told me a leaky exhaust could do cause the problem? But as I mentioned above, I have not noticed anything odd. How leaky would it have to be to fail on the lambda test? Enough that you would hear it, or are we talking very minor leaks? And would it make a sensor read higher or lower than permitted by the MOT?

Anyway, thanks again. Looks like I'll have to commit to the purchase and see what happens!

J.

MrDBM

hmmm, not sure about the leaky exhaust theory - but not too technical myself.

The lambda only takes it's readings on open throttle, which is why you passed the idle test. When I scraped mine, I made sure the CAT was very warm (some quick runs before testing) and it did fine - just. i would strongly suspect that as soon as you replace the 02, it will be fine.

A Scooby dealership could test the 02 for you, but reading your post you might not have time for that. Both the 02 and MAF have been talked about heavily, with conversations even suggesting that they should be servicable items, because they don't last out too well most of the time.

If your 02 were new, I'd be puzzled! Given that it's the original it's a pretty strong culprit!

69WRX

It could be a leak in the exhaust system.
Mine failed on emisions and it turned out to be a tiny hole in the downpipe under the heat shield.
I just put a bandage on and it passed.

SANTI

Good news guys!

Did a ECU reset, took it back & got a pass!!

CO 0.24% up from 0.00% pre reset
HC 6ppm up from 5ppm pre reset
Lambda 1.01 down from 1.06 pre reset.

Does this mean the car is capable of passing the requirements but gradually re-tunes itself to fail????!!!!

Thanks for your advice but it looks like I've scrapped through for another year!.

J.