My Service engine soon light is on and my screen is giving me a increased emissions warning. So I took my 2004 545i to a local part store to get the codes read and it seams that all four of my oxygen sensors are showing bad. I priced the sensors and it seems that the manufacture part cost about $242.00 a piece. Is this common for the upstream and down stream sensors to be bad at the same time? And if so what would cause this? Also I'm thinking about doing the work myself is there anything I need to know on how to D.I.Y.?

Please help labor cost $70.00 per sensor

Thanks,
Qtrtil6/545 owner

 

The Increased Emissions has nothing to do with the O2 sensors. You will get another error if it was an oxygen sensor. From my experience with my 545i is it could be a vacuum leak. loose gas cap, thermostat??<--- very questionable... There is a thread I started and another someone else started with this issue. Im pretty sure its not your O2 sensors.

 

Thanks 'Bimmerchop69' for your reply Im going to look into that before I spend 1,200 on parts and labor for the O2 sensors.

 

Update: I found I had a valve cover gasket leak and was loosing some oil. Thats when I found I had to change out the crank case hoses. I think that was the problem the whole time. Now my car seems to be running fine.

Thanks,
545i/qtrtil6

 

I was also getting the SES increased emisions fault. I replaced the VC and timing gaskets but the light came back on. There was another gasket on the lower drivers side of the engine that was pouring oil. After this was replaced the light has not come on. If you still have an oil leak after the gasket repairs check this gasket. It's very difficult to see behind the alternator support bracket without an inspection mirror and a PITA to replace.