Just had mot done and it failed due to co2 emissions being high (up and down apparently), not that I dont trust my local garage, but they're saying replacing the lambda sensor? That right?

 

That's one reason, yes.

A faulty or failing O2 sensor will cause all (or some) of the following:-

poor idle
poor fuel consumption
high exhaust gas emmissions

It basically runs the car rich (too much fuel), hence all the above. Have you noticed your tailpipe any sootier than nornam?

Only way to know for sure is to fit a new one or measure it's output voltage (either via a digital multi-meter or select monitor/deltadash (depending on MY).

Stefan

 

Just to add, it could be your cat(s) that are knackered - you do still have them in place, right?

Stefan

 

I was wondering
When you have a full decat, do they do away with the lambda sensor?

 

cheers for the replies

I never really looked at my exhast so couldn't really say if it is any sootier than normal tbh.
Is the sensor easy to replace or a job for my local scooby garage?

As for the cat, when I bought the car it had been to scoobysport for a centre section decat. From what I understand they're indentical to the std pipe from the outside, so i'm unsure as to whether it still on the car. Had no probs last year with the mot and nothings changed since.

I got a sinking feeling this is gonna cost a fair whack of money

 

You do not do away with the Lambda in a decat.
Reset the ecu but read any fault codes beforehand. From memory the Lambda is # 32.
Lambdas are available from BRD (Bob Rawle Developments) and cost a lot less than the £160 plus vat the local dealer quoted me.
Replacement is easy and unless the heat shield has to come off only needs a 22mm spanner. (10mm for heat shield)
Get the engine really hot before the gas analysis.
consider trying another MOT garage.

 

not to ask a stupid question, but how you reset the ecu? and get the fault codes?

cheers

 

What MY are we talking about here. Doesn't the location of the O2 sensor, it's type and number/location of cats vary between models?

See here for instructions on resetting your ECU.

Stefan

 

Does anyone know the part number for the Lambda on a wrx my93.

Is it four wires or just 2.

Thanks

 

Is it not possible to clean you lambda up with some cleaning stuff

 

is a MY99, I think i've found the lambda sensor, on the right side (looking from the front) of the downpipe, behind the turbo and heatshield.

 

Your MY99 came with two cats as standard - downpipe + centre section. If the centre's been removed and the DP left, it should pass the MOT emmissions easily. Mine passes with just the centre section.

Yep, that sounds like you've found it. I've circled the O2 sensor on the pic below just to double-check. IIRC they are £120+vat from a dealer.



Follow the instructions on my link to the MRT site for the ECU reset. When my O2 sensor failed it registered as error code 32.

Stefan

 

yep, thats it, I take it, its just a matter of undoing on the nut and unplugging it at the connector?

Can they be cleaned?

 

Yes. Be careful not to strip the thread on the sensor or DP. Use tons of pentrating oil and make sure the DP is v.cool.

You've nothing to lose by trying some cleaner on it, but only if your not going to get charged for the emmissions test. Doubt it'll fix it though.

Try Scoobymania and BRD for replacement O2 sensors as they should be cheaper than a dealer.

Stefan

 

Turbo dave I am having the same problem as you with my MY95 WRX and im sure that the only connector I can see that I would think is the lambda sensor one has got two wires ,a red one and a blue/black one. But I have been told that it should be either 3 or four wires :-(

 

Mark,

On a MY99, a failed MAF (very common on MY99/00) can cause MOT emissions failure - it did on mine. About £90 from the dealer... But the 02 is equally as unreliable, so could be that too.

MB

 

Cheers Mark,
I take it getting the error code will tell me which is at fault?

Cheers for everyones help

 

Possibly not, neither of these seem to give a CEL code unless completely dead... and dealers are useless at spotting these on a select monitor.

MB

 

Ozzy: Is your photograph reversed???