06 1.5 DCI Clio Check Injection

I bought a 06 reg Clio in march, about 10 miles into driving it the check injection light came on, i spoke to the person who sold me the car, he said to put some premium diesel in it then it should clear it out. after a couple of days the car was fine. last week the check injection light came back on, straight away i could feel the difference from the last time, when you start the car there is no power when you pull away, it struggles to 70mph on a flat motorway.

Now the check injection light doesn’t come on until you get to about 60mph but you can still feel there is no power.

I’ve seen suggestions to go as high as i can (safely) on the revs i got to about 55-60mph in 3rd and was about 3.5k -4k revs and there was quite a bit of smoke coming out the back, the smoke wasn’t black, but it wasn’t white.

I’ve seen people/websites say to clean the EGR valve, so i took it off and i was expecting to see it being clogged up with dry carbon.

the only way i could describe it was a clotted oil. I’ve no idea if this is normal or if this is what could be causing the injection problem.

I have seen quite a few people say they have taken their car to the garage for similar reasons and its 4-5 trips and quite a bit of money before it gets sorted. so i am trying to rule out as many things as possible before I take it in.

Any suggestions/Advice is greatly appreciated.

EGR could be clogged with carbon. Clean it and see if code clears.