Hi Guys,

2005 XC90 V8. Wife got a red ! warning light together with a red battery light and a message that went something like: "Power System Failure. Service Urgent." When the vehicle got home I could not get the warning lights back on nor the system message to repeat. A day went by and then it threw the following error codes: P0154 and P0134.

My OBDII scanner indicates o2 Sensors (P0154- Bank2 Sensor 1 and P0134 - Bank 1 Sensor 1 respectively). Questions:

1. Are the two incidents related? E.g. would the volvo throw the red battery and ! warning lights for an O2 sensor issue?
2. How many o2 sensors are there on the V8 engine?
3. any advice on replacing the sensors? Go OEM or general fit? procedure (e.g. disconnect battery, or anything special?)

Thx!
Dennis