MOT emissions fail

[subaruchic84]

Hi 

I bought my 1st Scooby in Sept 2015. It has a full decat exhaust system which unfortunately failed MOT emissions test!
The engine management light came on the day before MOT so thought I would put through MOT anyway & see what came up.
Emissions reading were as follows

Fast Idle Test
CO: 0.563 Fail
HC: 51 Pass
Lambda: 0.999 Pass

Second Fast Idle Test
CO: 0.672 Fail
HC: 44 Pass
Lambda: 0.992 Pass

Natural Idle Test
CO: 0.650 Fail

I had a scanner on to see the fault codes. 2 codes P1410 & P2433.
This suggested the secondary air intake pump & was advised from my local garage to take to Subaru specialist. 
Booked into Subaru for diagnostic (£85) WOW!!!  EXPENSIVE!! 
They also suggested same fault. They stripped it down and found out that it was fine. They suggested replacing a relay which they have now done. Checked emissions test again & said it was still high. Also mentioned that having no cat was going to make a big difference & probably won't pass an MOT without one.
They have suggested having a pre-cat fitted at turbo end . The question that I would like answered is: is all my emissions trouble going to be resolved by having a pre-cat fitted & will it pass MOT after? It is obviously going to be an expensive job & I'm worried that I will spend a lot of money to not resolve the problem. With my Scooby at Subaru it is costing me a small fortune!! Up to £300 already & nothing fixed!! 

Any help/advice will be appreciated. Thank You  

[The Don]

Almost certain to fail emissions without any cats present.

Most people with decatted exhausts refit at least one of the cats for MOT testing.

Has it been re-mapped to take the decat exhaust into consideration??

FYI

http://secondaryairinjection.org/2015/02/14/explaination-of-the-subaru-secondary-air-system/

 

 

 

 

[stano4130]

Hi.

I had a similar problem with my car, failed MOT due to no CATS being present.

The Hawkeye only has one CAT located on the downpipe from the turbo

I replaced the entire 3" exhaust with a new  2.5" Cobra system with 200cell sports CAT or so was meant to believe, CAT it self was really small and on test day, the car failed again.

After some hard driving and some heavy revving it finally passed by the skin of its teeth.

Full exhaust cost me about £700.

Had I known then, I would of gone on ebay, bought a used OEM downpipe which could be picked up for a few quid have it fitted to pass emissions then remove

after. 

 

[davey l wrx]

I'm having the same problem with mine. Been in the garage for 2 weeks now and won't pass the emissions test. I've had an engine light on for over 12 months but was told i'd had a mouse under the bonnet and a wire or 2 had been chewed and the fault was on an O2 sensor - they'd checked it and all was well.

Turns out it was the Lambda sensor - now changed £550 just for the sensor. But they now think due to the fault the car was slightly over fuelling and thats ruined the CAT. Now waiting on the price of the new cat to onto the bill for the service, MOT, rear brakes and sensor (already sat at about £1,400). I've got a full Milltek system from the down pipe back fitted so lord knows what this is going to add to the bill.

Usually it passes with some engine flush / injector cleaner and a little run to warm the cat up properly. 

Nice big bills like this have me looking at alternative cars it has to be said!