i have a 2005 beetle 2.0 convertible automatic. 50k, recently repaired leak at the coolant temp housing. with in a week the check engine light came on, 2181, replaced the temp sensor with a vw part green top sensor, cleared faults check engine came back after a week. same faults this time with 0118 and 3041. i flushed the coooling system bleed aout all air. car never over heated, just the check engine light came on. also noticed the check engine comes on at a cold start, if the ac is used takes about 2 weeks for the light to come on if no ac is used about a week.... any help around this issue?