This car has failed the MOT emissions at 1.9, mot plate limit is 0.54. There is visible black smoke during test.
Car has done 47000 miles and runs well, carried out a regen and engine service, smoke tested intake and no leaks found. I can only assume now that it has bad injectors and over fuelling or a restricted intake, if I go down this route I could be opening a can of worms and a massive repair bill.
What would be your next steps?

did the tester folow the purge procedure properly ?

you dont test at WOT

How to test:

Make sure the engine checks are satisfactory.
Make sure the engine temperature is above 80 degrees centigrade or at its normal operating temperature whichever is lower.
Make sure you've removed any oil temperature probes.
Increase the engine speed to around 2,500rpm or half the maximum engine speed – use whichever speed is lower.
Keep the engine at this speed for 30 seconds – this should fully purge the inlet and exhaust system.
Increase the engine speed slowly to maximum engine revolutions (revs) to check that the governor is working properly
Once the engine speed has stabilized or it becomes clear that the governor isn't working, release the pedal and allow the engine to return to idle.
Stop the engine and prompt the meter to do a zero check.
Insert the meter fully and securely in line with the gas flow.
Restart the engine.
Following the meter prompts, press down the accelerator pedal quickly and continuously so that the engine reaches full fuel position in less than one second.
Hold the engine at full fuel position until a release prompt is given and immediately release the accelerator pedal.
Allow the engine and any turbochargers to return to idle.
After the first acceleration read the smoke level displayed on the meter.
If the smoke level is above the limit for the vehicle, carry out 2 further accelerations.
If the mean smoke level is still above the limit for the vehicle, carry out further accelerations up to a maximum of 6 in total and read the smoke level display on the meter after each acceleration.

The vehicle has passed the opacity test if any of the following happens:

the first acceleration showed that the smoke level was at or less than the limit for the vehicle
the mean smoke level from the first 3 readings was at or less than the limit for the vehicle
the mean smoke level from any consecutive 3 readings was at or less than the limit for the vehicle

If the smoke levels from the first acceleration were significantly higher than the limit, you can choose to abort the test.

On vehicles fitted with a diesel particulate filter, also check that no visible smoke is emitted from the exhaust during the metered check.

Yeah sorry, I worded my post a bit wrong. The problem is the car, not the tester.

Hi
No chance it has been mapped and /or dpf removed?


Aidan

Have had a good success rate on MOT emissions failure problems with the induction clean the DPF Doctor now offers.

Have seen several cars emissions drop significantly following a clean and on to a pass.

Hi Aidan, no it's an old couples car, had it from new, dpf is still there and in good condition.

I'd suspect bad servicing in the past (wrong oil), and slow speed/ low rev driving has allowed a high level of soot to land inside the exhaust system, and it's now getting expelled during the MOT.
Personally, I'd add a good quantity of diesel fuel system conditioner (half in the filter - half in the tank, and take it for an Italian Tune (right good thrashing)!!