Stumped!!

[2 of the left]

My ECL came on over a week ago - On running the engine there have been no expensive noises - Diagnostics done - Code 0155 = o2 sensor heating circuit - So into the garage goes the 2 - Fixed  (All singing - All dancing) Took the 2 for a burn ( approx. 10 miles ) ECL re - appears - What is causing this???   s:? :? s:?    s:? :? s:?    s:? :? s:?

[Ardent]

same code?
Correct sensor replaced?

[2 of the left]

Ardent- Will find out on Monday