Hi

I need a bit of advice regarding my STI 3. It's failed the MoT on emissions - the Lambda reading is 1.04 (should be 0.97 > 1.03). It had a new lambda sensor and MAF sensor 3 years ago - about 20,000 miles ago.

The garage have said that the centre pipe has a tiny hole and also reckon that the joints could do with new gaskets. It's not running particularly smoothly (new platinum plugs 15,000 miles ago) but to be fair it's only done 200 miles this year and all on short journeys so it could be a bit coked up.

One option is to get a new centre pipe (de-cat) and gaskets. Do you think this will help it pass or make no difference. And what about a bottle of injection cleaner and a 20 mile blast.

Or could it be the cats on the way out? As ever, what's the cheapest option to get through the MoT?

 

injector cleaner and a good thrash?

 

what are the HC's and CO levels?

 

I'll find out about the HC and CO later, but they did pass.

 

HC was 25ppm (limit 200) and CO was 0.02% (limit 0.3%). Lambda 1.04 (limits 0.97>1.03)

 

A new centre pipe has made things worse!

Any ideas on what to try next?

 

could still be the lambda sensor. I would put money of that 1st, then the cats.

Stefan

 

It's now passed with a reading of 1.01.

The answer: a bottle of injector cleaner and a 70 mile drive.

Thanks for your suggestions.