My bmw n52 engine 2.5 inline 6 recently gives fault codes on both cats below efficiency. 1 cat per 3 cylinders.
I can clear the codes but after a couple of miles the codes come back, strangley the always come simultainsly on both cats.
If i clear the codes, let the car sit for the night they are away for like 10 miles. But then they re appear again, like the ecu is doing some kind of check then after warm up. This is only when i drive like 60mph. If i head in to town they will stay away longer.
I have changed the pre cat lambdas because officaly their service life is only 150k miles but this didnt help.
I wont spend a ton of money on this because emmisions are fine and it runs like it should.
Milage is now 230k miles with oil consumption of around 1qt per 2000 miles.
Car is driven hard for long distances, a lot of 120 mph highway runs.
Car has always been filled on ll04 spec oil for all its life.
The last 80k miles where on shell helix am-l 5w30.
Could oil have killed my catalysts or is there something else going on. I have read up on clogged catalysts but then you would also lose power.
As i said the car is driven hard so you would assume this would be burned out all the time.
Does anybody have experience on this?
I can clear the codes but after a couple of miles the codes come back, strangley the always come simultainsly on both cats.
If i clear the codes, let the car sit for the night they are away for like 10 miles. But then they re appear again, like the ecu is doing some kind of check then after warm up. This is only when i drive like 60mph. If i head in to town they will stay away longer.
I have changed the pre cat lambdas because officaly their service life is only 150k miles but this didnt help.
I wont spend a ton of money on this because emmisions are fine and it runs like it should.
Milage is now 230k miles with oil consumption of around 1qt per 2000 miles.
Car is driven hard for long distances, a lot of 120 mph highway runs.
Car has always been filled on ll04 spec oil for all its life.
The last 80k miles where on shell helix am-l 5w30.
Could oil have killed my catalysts or is there something else going on. I have read up on clogged catalysts but then you would also lose power.
As i said the car is driven hard so you would assume this would be burned out all the time.
Does anybody have experience on this?