Hi I fixed a ecu faults the other day it started 1st,2nd,3rd time all good turned it off sorted insurance n tax out went back two days later and not starting , had the battery test it’s 100% no fault codes anyone got any ideas 

Starter motor?

I have fault code p 0688 p2249 I also had when 1st done it 2149 and 2146

Thank you I am abit of an  amateur but I will look for these fuses and check them , I just hope it’s not the ecu , Skoda told me 2k !! I ant got that sort of money :(  

P2249 was p2149

I had a fault with it before hand it wasn’t starting I changed the relay 644 and it worked from 13 faults to 0  and started abit rough at first but then felt fine ...left it for 2-3 days went to pick it up and nothing at first I fort the battery had died but got that tested it was good ,  so now I don’t know really where to start , I’m guess fuses then injections , then wires but how do I check each wire , I pulled the ecu it was in the car via a tie wrap open to all the elements, it’s looked ok just a few white spots , the last owner said the ecu was tested but they couldn’t find a fault , it’s a nightmare

You've not given us anything to work with really. Basics first. What car and engine, petrol or diesel, what are the symptoms of "not starting"?

Does the engine turn over but it doesn't fire? Does it not actually turn over at all?

Skoda Octavia 2.0tfsi 2006 petrol replaced a relay 644 it worked well started first time then yesterday didn’t start at all had those 3 fault codes come up cleared them and still doesn’t start just turned the key and it cranked alittle but not enough to get it started

Are you sure the battery is good?

 

Who tested it and gave it a clean bill of health?

 

If the car is actually cranking, albeit slowly and not for long would suggest the battery / starter motor, rather than fuses, connections, switches etc.

Can’t believe this !! Car working again with no fault codes battery 100% was tested by a trustworthy person

Check for corrosion on battery leads to body connection.

Have you gone and driven the car yet? Do a 100mile drive to get it up to temp and going.

 

this car has been left, your current issue is shouting bad battery. A long drive will charge it and get everything flowing through the car.

I’m way too scared to take it out atm I know it need a good run but I can’t risk it yet