Master Oxygen Sensor Fault

I own a Renault Master, too, and had a similar oxygen sensor issue. Was your air-fuel ratio off? Mine was, possibly due to an exhaust system problem.

Yeah, the air-fuel ratio seems off. Exhaust smells richer than usual. Did you resolve your issue? What was the cause and fix?

My issue was a defective connection, like you suspected. Since the symptoms are similar, I'd take your Master to a reliable workshop to inspect the oxygen sensor wiring and connection points. Rule out any further damage.

Thanks! I suspected a bad connection, and your experience confirms it. I'll get it checked at a workshop. Got a quote of 95€ for the repair, which sounds reasonable. Appreciate the help!