MOT FAIL - Emissions

Reborn · Post by **Reborn** » May 22nd, 2007, 4:40 am

Just had about £900 work done on my car to get her back on the road again after taking it of for 6months.

Suspension, Braked, Oil/Fuel filters, New Clutch (MX-6) and other things.

But its failed the MOT on its emissions, 2nd Fast Idle, I have a Custom exhaust which isn't especially mad, its just a twin 3.5"

I'm concerned i have a dodgy 02 sensor or perhaps something worse....has anyone got any experience in getting a car through its MOT with this kind of problem

MX3ak · Post by **MX3ak** » May 22nd, 2007, 9:41 am

V6, right?

If the problem is Idle, you can adjust to specification (650rpm) by puting in diag mode plus adjust screw on throtel body.

If the problem is variable idle (up, down) the you got a leack in vaccum system. Check every air hose aroud intake manifold.

If the problem is emissions, check catalytic converter.
But maybe to much oil burning too. then only solution is new head gaskets or/and valve steams.

Best luck!

Reborn · Post by **Reborn** » May 23rd, 2007, 3:29 am

Not that, apparently its needing two new Lambda sensors also known as 0xygen Sensors for the exhaust..........that explains why she's been running rich recently.

So thats £153 per sensor...ouch!

capamx3 · Post by **capamx3** » May 23rd, 2007, 6:28 am

Are you sure that the sensors are bad, not only just an error in the diagnostic box?

Reborn · Post by **Reborn** » May 23rd, 2007, 6:42 am

The garage is pretty sure its the sensors yeah.....

Sounds about right its had all the symptons, hesitation under acceleration etc.

MX3ak · Post by **MX3ak** » May 23rd, 2007, 7:00 am

If it´s the Lambdas error on the Diag, then yeah, better replace those. Then reset ECU.

You can get them both for less than 50$ on ebay. Universal Mazda 4 wires.

Reborn · Post by **Reborn** » May 23rd, 2007, 7:58 am

Thanks for the assistance!!!