P0130 o2 sensor 1 bank 1 circuit SKODA Octavia I Hatchback (1U2) (09.1996 - 12.2010)

Hello, i am getting the error code p0130 for my skoda octavia 1u2 from 2004 with engine code bfq. Live data of the obd reader reads 1.4 volts for o2s1b1 signal (also when the lambda is detached). I suspect a short circuit but maybe somebody with knowledge has more ideas. The lambda was replaced a year ago for this specific error code. The engine light stayed off after replacement of the lambda till last summer when it lit up again. Noteworthy to mention that there was an event about 1.5 years ago when a strong burned smell of plastic was observed for a brief amount of time. And i think that the engine light went on shortly after this event. How to spot a short circuit location?