E39 o2 sensors again?? fuel gone up the hill

[SonGoKu619]

Hi, I've posted previously concerning an e39 540i which had horrible fuel consumption even when driving with a featherfoot (20l/100km). Engine light went on and it turned out to be the o2 sensors...I took it back to the garage i bought it from (Bryanston executive cars) and they replaced it. I drove it for a week around town and I was getting excellent fuel consumption (11-12/100km) and this was after a few re-calculations on the OBC in town...Then one morning..I get into the car and WHILE idling I check my fuel consumption hiking again..I've been driving it for a week at 18-19/100km...

Any ideas??

 

[P1000]

Were they replaced by new genuine bosch O2 sensors? Did you use leaded fuel?

 

[SonGoKu619]

I doubt it was the fuel, but I will call up the guy on monday to check which sensor they put in...

 

[Beast_Power]

Sounds like the cats have gone for a loop, as a result they get very hot and fry the sensors. Think it is time to decat !

 

[SonGoKu619]

I was looking for a reason Harr! lol..Will update s00n