Diesel emissions limit

[osx]

When did the emissions limit change for diesel cars? What are the limits for Euro 5 vehicles. The X7 failed emissions this year but looking at previous MOTs the levels were about the same so it must be the new limits that are causing so many diesels to fail emissions testing.
The DPF seems to be in good health as 90% are motorway miles, oil and filter change every 6-12months so not sure what else can be done to reduce emissions. Have cleaned the EGR valve but not the EGR cooler (can this cause problems?).
At the garage they added something to the tank to help but wanted to check if I should check anything else while the additive is doing its job.

[GiveMeABreak]

So looking at the MOT manual extract below, you can see diesels from 1/7/2008 (which will include the C5 X7) have basically had their smoke test limits halved and even less from vehicles registered after Jan 2014 as in my case. I always bung in a tank of premium fuel every month or so to keep the fuel system clean. Mine will be due it's first MOT next December, so will be interesting to see what the reading is compared to the low level of 0.7m-1 allowed now.

From The Express:

Diesel vehicles have seen the greatest surge in MOT failures based on emissions issues after a massive 240 percent rise over the past five years. A total of 420,537 diesel vehicles failed their test as a result of an emissions-related fault between 2019 and 2020 compared to just 118,302 cars between 2015 and 2016.

From National

Reducing diesel emissions
There are a number of ways that can help reduce diesel emissions. These tips below will a great benefit overall to ensure your car is fit for purpose and also ensuring that during your MOT test, you are able to pass the MOT emissions test.

Regular car servicing
[Servicing Ad Removed]

Use premium fuel
Premium fuel is more expensive than your standard diesel however it does an excellent job in reducing diesel emissions. Premium fuel has fewer chemicals which helps your car’s engine run smoothly. With standard diesel, the added chemicals can result in an increase of soot which would clog up your diesel particulate filter. To find out ways to save money on fuel, please click on the related article below.

From the MOT Manual - Smoke Meter / Opacity Test

For vehicles first used before 1 July 2008, the maximum level is:

2.5m-1 for a non-turbocharged engine
3.0m-1 for a turbocharged engine
For vehicles first used between 1 July 2008 and 31 December 2013 the maximum level is 1.5m-1 for all engines.

For vehicles first used on or after 1 January 2014 the maximum level is 0.7m-1 for all engines.

Manufacturer’s plate means either the VIN plate or a separate plate or sticker, which is likely to be within the engine compartment. The plate or sticker may be marked 24 R followed by a number to indicate the smoke limit (such as 0.24 in the example below). It’s usually displayed in a box and often positioned in the bottom right corner of the VIN plate.

[RichardW]

Pretty sure yours will be less than 0.7 Marc. But as long as the DPF is working, it should be near zero.

[osx]

Can a faulty egr cooler cause high emissions? Would a diagbox diagnostic pick it up?

[GiveMeABreak]

I doubt that very much, that's jut the cooler for the EGR and has no bearing on EGR operation that could affect emissions.

I'd be possibly looking at cleaning the air intake manifold as that could be gunked up, and putting a decent diesel fuel system cleaner in for the next few tankfulls, but making sure it is well up to temperature before the MOT and that it has had a good run before hand to clean the tubes out as it were.

[osx]

If you have coolant leaking in the EGR cooler wouldn't it evaporate and find it's way via the EGR in the engine/exhaust?

[GiveMeABreak]

Pretty sure yours will be less than 0.7 Marc. But as long as the DPF is working, it should be near zero.

Yes, I've no reason to suspect it won't. It's a Euro 6.2 so has quite stringent limits, but will be interesting! Apparently there are a huge number of things Citroen will cover under the MOT Warranty I have if it fails at first MOT, so that is also extra peace of mind.

[KennyW]

Just my recent MOT emissions test and 0.30 M-1 result with a drift of 0.2m-1 pretty good for my C5 with 186,000 miles on the clock.

You will identify the problem but I agree with Marc put premium diesel in every month or so does help.

On my trips to France I do it when I leave home and then once on the return journey.

Kenny

[RichardW]

There hasn't been a change since the new rules were introduced in May 2018. So if the emissions are the same, then it was either a false pass last year, or the numbers are wrong this year! What emissions number did it come out with? A DPF fitted car should be almost zero, is there visible soot in the tailpipe?

[bobins]

Hasn't the 'formula' for regular diesel changed in the last year ? More 'bio' in it now than before ? Or am I mistaken ?

[osx]

There hasn't been a change since the new rules were introduced in May 2018. So if the emissions are the same, then it was either a false pass last year, or the numbers are wrong this year! What emissions number did it come out with? A DPF fitted car should be almost zero, is there visible soot in the tailpipe?

That's what I thought - passed 2019/20/21 without problems. The emissions number they were looking at has to be <0.51.

Found the 2019 emissions and mean was 0.39

[RichardW]

0.51 sounds about right, there should be a sticker under the bonnet somewhere with the number in a square. What reading where you getting? Take it for a good hard thash, and it might get through, but if it's well over DPF may be cracked or something.

[osx]

First time about 0.9 - after I cleaned the EGR and replaced air filter it came down to 0.55 but soon after they added the fuel system cleaner it went up to 0.9 again. Done a few motorway miles with engine reving @3500-4000 and filled with Vpower. Let's see if this makes a difference.

[osx]

Finally passed emissions after two tanks of Vpower, additive and a couple of runs on 3rd gear and 4,000 rpm. Thought about having the injectors cleaned/replaced if it failed again but will probably stick with using that additive every 3 months. This was probably the penultimate MOT.