hi, i just put my car through its MOT and the car failed on emissions....

the car:
has a cat,
has been serviced very recently with no faults on the ecu,
has had a new MAF sensor recently,

when the guy at the garage gave me my keys he said it could either do with a service (obviously no need) or it could be the lambda sensor...

can anyone shine any light on the matter for me?? and if possible where i can get one without breaking the bank as i rung up Prosport (subaru specialist) and they want £49 ex vat for 1 hour labour and £90 ex vat for the lambda if it is that........

 

What did it fail on - CO2 or Hydrocarbons? Or was it visible smoke?

 

sorry i forgot to add that i have UK turbo 2000 (1999)

and it failed on CO2 i think

 

Give these guys a ring

API Engines

See if they have a cheaper option for the Lambda sensor, then find the cheapest local garage/exhaust place you can find to fit it for you. It's not a difficult job that needs a specialist.

 

If the ECU hasn't been reset since the MAF change, it may need to be - they don't appear to notice if the MAF has been changed & it may be ignoring the reading, which is fairly likely to cause an MOT fail... Might need a new lambda probe anyway as if the fueling's been off because of the dodgy MAF, it could've screwed it. You can easily tell if the ECU wasn't reset after the MAF change as it'll drive quite differently (and typically the idle will improve, unsurprisingly!).

 

The lambda sensor screws into the downpipe catalyst and it can be viewed from the top of the engine bay, on the right side of the pipe a few inches below the turbo. To remove it, unplug the connector block, lube up the thread and use a 22mm spanner. It may not want to budge though.Mine trashed the thread on the sensor while removing it.
It's well worth sourcing your own parts and fitting yourself.

 

hi do you think it can be the lambda sensor even tho there the ecu is clear and the engine light is not on?

 

The ECU will only show if there is a complete failure - it won't notice a misreading sensor. Knowing the reason for the failure is pretty key - here's a 'guide' for working out where the problem is (might save you some cash!):

1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3. if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5. if the Lambda (reading) fails then... if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.

 

oo ok thank you

il find out in the weekend when i have time to check things out.. i hope it just the lamda sensor... a cat or a remap could be quite expensive since im looking to sell the car after i get the new MOT....

il post my findings when i know more

 

Great i found out its just a lambda sensor

now i need to order one and fit it

 

lambda sensor in, mot done, car has passed car also for sale again in the generals section

 

Is it any other way to pass CO2 with decat 3" system ? I just fail MOT and i need to find the solution ...

 

with a decat u will never pass the mot its either friendly station/sports decat downpipe or cat on mot cat off after mot

 

I think that i found solution Nemesis UK: "MAGNAFLOW - Street Racer Cat Cent 3"" Bore" What You think about ??

 

would ^^^^ work? mine has a decat downpipe and i desperately need a cat and a lambda sensor to go in so that it passes! let me know please someoneee!