Failed MOT on emissions but only just!

I took the 996 for an MOT on Tuesday, I had checked the car over and couldn't find a reason for it to fail but it did and on emissions. I haven't driven the car since last July/August time and this was it's first drive since then, straight to the MOT station! I did take it the long way around just to get the engine warm as the 1 mile to the MOT station wouldn't have done this. I've had issues before with emissions and only just scraping through its test but since then it's passed without a problem and I have changed many parts since then. Most parts fitted 2018 and service parts start of 2019 and only around 3000 miles ago for the service items. 4 x lambda sensors catalytic converter (original had collapsed) tank vent.vac pipe purge valve fuel filler/bleeder valve MAF plus oil service filter service spark plugs coil packs Because the MOT expired in December 2019 I can't really take it out for an "Italian tuneup" which is probably what it does need? Since I have got it back in my garage I plugged the Durametric in for codes, immediately I had two codes referring to the lambda adaption on both banks, I cleared these and they haven't come back, just running it at standstill? I have pulled the spark plugs and they look fine, these are from bank 2 and all three were the same. And the live readings Anything look out of order in any of the above or any thoughts, I'm scratching my head to why it failed?

My car had the eml come on last year and I had codes p0172 and p0175. My lambda were both 1.0 and it passed its mot no problem. The codes are for idle range fuel trims (rkat) being on the rich side so the engine management has subtracted as much fuel as it can and then set the code to tell you it has run out of adaption range. It pus the lamp on at around -4% or plus 4% if it was lean but you'd have different codes obviously I'm my case both of my rkats were negative which agreed with the codes. In your case, as is typical of any fault you ever post about lol !!! You have codes for being rich at idle on both banks yet one of your rkats is negative which means fuel has been removed and the other is positive which means fuel is being added. I'm my case I checked the car was free of boost leaks and as the o2 sensors all looked lively enough, and as the maf voltage was slightly high but still within porsche diagnostic range, I decided to replace the maf and that fixed my fault. My rkats are below 0.5% now. Ps my maf had only done 20k miles and I have only had standard filters which had been changed every 4k miles so didn't expect the maf to be faulty but it was. Ps the upper fuel trims frau and frou sits at 1 when no fuel is being added or subtracted. So 0.8 is quite a bit removed and 1.2 would be quite a bit added.

I would try driving it a bit then taking straight for another test.

I just had a look back when I changed my MAF, its only 16 month old and I guess has done less than 5000 miles and I made sure it was a genuine MAF before buying. I did clean the MAF yesterday just because I had the airfilter box off to check the throttle body wasn't oiled up, it wasn't and was a lot cleaner than I expected. I also checked the oil filler cap was sealing correctly and it was. While I have the spark plugs out I have also changed them even though they are low miles, (I boreoscoped the engine while it was open, still looking OK) On the RKAT figures you mention, I hadn't noticed the 4.03 was a negative figure, I thought it was almost in sync with bank 2? I'm going to check my readings again later today to compare since I've messed with things since yesterday.

I wish I could but I don't want to get stopped for no MOT, from the MOT station and back I am covered if I'm booked in but as it expired last year I can't just drive it. I do think to some extent it needs a good, hard drive?

Do they check levels from both banks or just the 1? Would be interesting to see if one side is a fail and the other a pass. Even so, you can't beat tenner bung when you have issues like this.

Usually I would be there having a good nosy under the car or even helping with the MOT test but due to distancing I had to do one while they did the test so I'm not sure which bank they tested from. Unfortunately the computers are now supposed to be connected to VOSA as far as I'm aware, or at least the result automatically get sent to them, so you can't fudge the results unless you use another car for the test?

Local well known outfit round here passed my mate's Maserati without even looking at it as they were busy, he was booked in and it was near closing time so I don't think they have to submit results.

These new emission regs are a pain , mine struggled to pass last time, take it for a good run really warmed up first add some additive to the fuel and get them to MOT it the second you arrive . should be good then . :thumb: :thumb:

He can't Phil without risk of getting done. The car's MOT expired before 20th March, thus making it illegal to drive anywhere but to the garage or test centre.

Just had a read up now - connected equipment is only compulsory if it is being renewed. When is Connected MOT Equipment Going to be Introduced? Connected Equipment is a big change for the industry and one thing is clear, the DVSA is not going to make it compulsory for existing Vehicle Testing Stations, with equipment already in use, anytime soon. However, from 1st October 2019 MOT stations making a site application or replacing an old brake tester will have to purchase Connected Equipment. Following this there will be a phased approach for emissions equipment, beam setters and decelerometers. ARTICLE UPDATE: A DVSA email bulletin sent on 01/11/2019 confirmed the following timelines for the introduction of other items of connected equipment: Decelerometers - 1st February 2020 Diesel Smoke Meters - Late spring 2020 Exhaust Gas Analysers - Late spring 2020 Headlamp Aligners - Summer 2020 At some point in the future the DVSA will need to make Connected Equipment compulsory for all testing stations but this is likely to be some way off.

They did say there is nothing they can do to get it through as it gets sent to them, so I assume they have updated their systems, they are a big chain. One of the lads came over to me when I was leaving and he did suggest I tried somewhere different that one of they guys who used to work there now works? Or book somewhere a bit further away to give a good run to get there?

:thumb: The group that passed my mates Mazzer own an OPC!

Any chance of small leak on any of the exhaust joins on that side? I chased a slightly high lambda (lean/too much air) like yours on a previous car and found reseating/sealing exhaust joints to solve.

I had a fail on one bank due to this a couple of years ago. Seems you've dived straight in instead of eliminating the easy stuff first. Good luck