The fault light had been on for a long time in my 2004 model Peugeot 206. The oxygen sensor appeared as a malfunction in the computer. While surfing the web today, I came across the sensor cleaning process. I cleaned and replaced the lower and upper sensors, replaced the battery terminal, started the car, but the fault light did not go out. After 1-2 minutes I saw smoke coming out from under the hood and I turned the ignition off and opened the hood. At first, I thought that the bolt of the oxygen sensor was getting stuck because of the wd 40 I had squeezed on that part, but when I looked carefully, I disassembled the battery terminal as I saw that the cable visible in the photographs touched the protection of the catalyst and created a spark there.
I have no idea what this cable is and what it is not. It seemed like a chassis to me, I would be glad if it illuminates with knowledge.
addemarch
sonerkyl