m4rcus

hi every1 hope some1 can help . car was running perfect then decided to change all hoses to red /get rid of a/c also new oil filter magnetec 10/40. now i have done this car run rubbish from cold sometimes cuts out but when warm its ok heating ok in car but when gets to running temperature check engine light comes on /but when i do test on codes it just stays at 1 sec flash all time... mystery to me i checked all pipes connected no wires off in need of help