which is the best way to diagnose this problem?
1 Fault Found:
008194 - Particulate Trap Bank 1 
              P2002 - 000 - Efficiency Below ThresholdIn-termittent.
ive cleared the code but coil light flashes about 5 mins into the drive. once the light has come on once then it wont come on again till ive cleared it. only thing i have noticed is when i happens is it feels like a slight misfire then back to normal. sometimes the car will smoke a lot but never goes into limp mode. Ive got VCDS and just wondering where i should start? Force a dpf regen? check sensors with measuring blocks? i know the previous owner had this problem and they tried changing the throttle body.

Definitely do a Regen. Unfortunately you may find you'll have to replace the dpf I'm afraid.

Cheers

Steve

I've done 350 miles since the fault happens last. Drove 36 miles to work this morning at 6.40 and drove fine. Came to park up and it started to smoke again. Came to the car 8 hours later and about 3 miles into the drive it started to smoke again. On the way home I've got a 5 mile up hill drive and about 2 miles in it stopped smoking and went back to normal. Did a scan when I go home and showed this :

8038
2 Faults Found:

008194 - Particulate Trap Bank 1 
               P2002 - 000 - Efficiency Below Threshold
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 2
                    Fault Frequency: 11
                    Reset counter: 255
                    Mileage: 352996 km
                    Time Indication: 0
                    Date: 2019.04.15
                    Time: 06:58:53

             Freeze Frame:
                    RPM: 2001 /min
                    Speed: 106.0 km/h
                    Pressure: 3 mbar
                    Hex Value: 0xFF01
                    Temperature: 270.0°C
                    (no units): 209.1
                    Mileage: 300 km

001348 - Sensor 1 for Exhaust Temp Bank 1 (G235) 
               P0544 - 000 - Circuit Malfunction - Intermittent
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 2
                    Fault Frequency: 11
                    Reset counter: 255
                    Mileage: 352996 km
                    Time Indication: 0
                    Date: 2019.04.15
                    Time: 06:58:53


Readiness: 0 0 0 0 0 

Are you sure about the dpf seeing as it's a intermittent fault ? I thought if the dpf was blocked then it would happen all the time 

Does it feel sluggish or down on power? 

I can't really tell as I bought the car with this fault. Only thing I have noticed a couple of times is a slight misfire feeling at around 4000rpm