Emissions MOT fail

[Chrisgti6]

Not on a Clio, this is on my MR2 Roadster.

Sent it for an MOT yesterday but it failed on emissions. HC and Lambda were a pass but CO was over. Picture of the results below. It did previously have an engine that was burning a whole lot of oil, so there is potential for there to be some residual oil in the cat & exhaust system - would this cause high CO or am I best off looking elsewhere? I have a spare cat and exhaust I can swap over and some spare lambda sensors if needed, although I do have a decent diagnostic tool so might check out the lambda readings before swapping them out.

Obviously I only get one shot at a retest so is there anything I can look at in my diag tool to indicate if I've reduced the CO? Post cat lambda readings maybe?

 

[Mr Trailer Man]

High CO suggests a rich fuel mixture, but then the HC (unburnt fuel) is way low 🧐

See what your lambda readings are.

 

[Chrisgti6]

High CO suggests a rich fuel mixture, but then the HC (unburnt fuel) is way low 🧐

See what your lambda readings are.

Yes the lambda and HC results being where they are suggest a good fuel mixture, but high CO says otherwise which is slightly confusing!

What should I be looking for on the lambda readings? It has 2 precat and one post - would I need to be looking at all 3? Looking at voltage fluctuation I assume? I know my tool can record the results so i'll have to risk taking it out without MOT and get some readings done

 

[Mr Trailer Man]

Yes the lambda and HC results being where they are suggest a good fuel mixture, but high CO says otherwise which is slightly confusing!

What should I be looking for on the lambda readings? It has 2 precat and one post - would I need to be looking at all 3? Looking at voltage fluctuation I assume? I know my tool can record the results so i'll have to risk taking it out without MOT and get some readings done

Yeah the precat should be fluctuating steady wave up and down.

Post cat should be a steady line/voltage.

 

[.Joe]

When was the last oil change? recently had one where just an oil change was enought to bring the CO down on the emissions

 

[Mr Trailer Man]

When was the last oil change? recently had one where just an oil change was enought to bring the CO down on the emissions

Could be a shout i've heard of that before.

Fuel in the oil from short journeys and being sat around.

 

[Chrisgti6]

When was the last oil change? recently had one where just an oil change was enought to bring the CO down on the emissions

About 5 miles ago . It had all filters, plugs, oil, belts etc when I put the engine in the car. It runs spot on so I can only assume the cat needs a proper clean out or swapping.

 

[thecrim22]

Stick an injector cleaner in and kick its c**t in usually works

 

[Dicky Belly]

Damage the emissions sticker in the door shut. Your emissions limit will almost double then and you’ll pass. (Works every time!)

 

[Louis]

Damage the emissions sticker in the door shut. Your emissions limit will almost double then and you’ll pass. (Works every time!)

 

[thecrim22]

Damage the emissions sticker in the door shut. Your emissions limit will almost double then and you’ll pass. (Works every time!)

Or get a decent mot tester😜😜

 

[Matt Cup]

Damage the emissions sticker in the door shut. Your emissions limit will almost double then and you’ll pass. (Works every time!)

 

[Dicky Belly]

View attachment 1757102

See the 0.37 in the bottom corner? Thats the manufacturers Emission limit. If emissions are over that, the manufacturer is basically telling the Tester that the car is faulty.
If you cover that 0.37 up with black pen or scratch it off, or cut the corner off - the limit then has to default to 0.7 as per the DVSA.

Le Bosh! 👌🏽

 

[R3k1355]

I thought the MOT manual starts the emission testing procedure by saying something like: "Find an exact match in the MOT database"

 

[Louis]

I thought the MOT manual starts the emission testing procedure by saying something like: "Find an exact match in the MOT database"

Yeah I thought this too?

Don't the regs just come out via the reg?

 

[Mr Trailer Man]

Yeah I thought this too?

Don't the regs just come out via the reg?

I'd have thought so or the VIN.

I've never seen a guy looking for stickers in the door shuts.

 

[Steve]

Didn’t know where to put this, but I know these discussions come up a lot.

There appears to be significant change on the horizon for the MOT, with not only increased costs for garages but also tighter regulations that could affect many motorists in ways that aren't currently a concern

Currently, an illuminated engine management light is a reason for failure, as it indicates a potential issue with the vehicles emissions system.

However, it seems this could be extended further to include direct interrogation of the ECU for fault codes that may not necessarily trigger a warning light.

There also appear to be plans to introduce readiness checks, which would prevent drivers from clearing fault codes shortly before an MOT test in an attempt to avoid detection.

So does this mean all those with CAT delete DPF & EGR code outs would be failures!

 

[Klumpy Dumpy]

No because most proper people that map out dpfs etc are removing the entire logic blocks from the ECU by telling it that it never had one

All it is, is even more strictness on older cars so they can move people into newer cars

 

[botfch]

Easy solution.

 

[R3k1355]

Haven't they talked about this previously, but the cost was never worth it?

How do they think these readiness checks will prevent someone clearing DTCs before they arrive at the testing station?

 

[BashRacing]

When I was at Vosa it was suggested but sacked off due to the risk of bricking ecu's and who would stand the liability.

 

[McGherkin]

Haven't they talked about this previously, but the cost was never worth it?

How do they think these readiness checks will prevent someone clearing DTCs before they arrive at the testing station?

On most OE ECUs, clearing DTCs resets the emissions data and the car has to drive multiple cycles in order to satisfy itself that it passes the readiness checks.

If you clear DTCs before driving to the testing station the car will say it’s not ready when you plug it in.

 

[leeds2592]

Yet more scaremongering. Next they’ll be saying they’ll employ someone @dann2707 size to jump up into the exhaust and have a walk up it to check the dpf is still there

 

[McGherkin]

Yet more scaremongering. Next they’ll be saying they’ll employ someone @dann2707 size to jump up into the exhaust and have a walk up it to check the dpf is still there