540 O2 sensor replacement Q's

[onewhippedpuppy]

This weekend's project is the front two oxygen sensors in my 540, it's been throwing CELs, and idling rough along with the light. Plus, I think they're original, and at 130k it's time anyway. Should I expect to partially drop the exhaust, or can I get to them without? Do I need to get the little sensor socket, or can I get a wrench or crow's foot on it? I just want to get prepared today, the dealership isn't open Saturdays if I end up needing exhaust gaskets.

As an aside, I found sensors at O'Reilly's for $52 each, they're the splice in type. They're Beck Arnley branded, but I'm not sure who makes the sensor. They have a number stamping on the hex section similar to many Bosch parts, makes me wonder. I've found lots of good stuff at O'Reilly's cheap, when I did the CV boots on my 951 the box was an off brand, but the boots were OE Lobro. Half the price I could get them for elsewhere.

[shogun]

http://www.bmwe34.net/e34main/maintenance/gen_maintenance/o2_sensor.htm
And here my one in Japanese for the E32 750.
http://infinitier.ddo.jp/e32/page/mainte/mainte_056.htm
Also did not drop the exhaust. Just removed the 2 bolts at the rear, then pushed up the middle of the exhaust with a hydraulic jack to get the rubber ring holder form the bracket for the exhaust, removed jack, let the exhaust hang down and then unscrewed it with a normal open wrench. Had no problem, except I mixed up the 2 connectors, and first had the oxy sensors connected across = left side exhaust to right bank and right bank exhaust to let bank. Took me a while that I found out what I did wrong. Engine was running terrible. So had to go again under the car and connect correctly.
For that I recommend to mark the connectors before you remove the oxy sensors to avoid mix up.

[onewhippedpuppy]

Thanks, so I either need to pull the bolts to get some wiggle room for a wrench, or pick up the sensor socket?

[Shaun]

This weekend's project is the front two oxygen sensors in my 540, it's been throwing CELs, and idling rough along with the light. Plus, I think they're original, and at 130k it's time anyway. Should I expect to partially drop the exhaust, or can I get to them without? Do I need to get the little sensor socket, or can I get a wrench or crow's foot on it? I just want to get prepared today, the dealership isn't open Saturdays if I end up needing exhaust gaskets.

As an aside, I found sensors at O'Reilly's for $52 each, they're the splice in type. They're Beck Arnley branded, but I'm not sure who makes the sensor. They have a number stamping on the hex section similar to many Bosch parts, makes me wonder. I've found lots of good stuff at O'Reilly's cheap, when I did the CV boots on my 951 the box was an off brand, but the boots were OE Lobro. Half the price I could get them for elsewhere.

I got my O2 sensors off with a couple jackstands up front and a 22mm (I think) wrench. Didn't have to drop any exhaust parts or anything.

Did you check your intake boot right at the throttle body for cracks or holes? This ended up being part (or almost all) of my problem with a REALLY bad idle and the CEL coming up constantly.

[garretb]

Same here. I drove up on Rhino Ramps, unscrewed one end and unplugged the other of each sensor, and replaced with the new ones.


I got my O2 sensors off with a couple jackstands up front and a 22mm (I think) wrench. Didn't have to drop any exhaust parts or anything.

Did you check your intake boot right at the throttle body for cracks or holes? This ended up being part (or almost all) of my problem with a REALLY bad idle and the CEL coming up constantly.

[scott540]

No Need to drop the exhaust on the 540. sensors are on the sides. Even I was able to do it. Soak em good before you try to loosen them though.

[onewhippedpuppy]

Thanks guys, easy as can be. I also found that the throttle body elbow was half off, which is scary, so I took the opportunity to clean the throttle body and ICV. I also did the ECU reset. Runs smooth now, with no CEL, I'm happy.

An aside, is it supposed to be a bitch to fit that TB elbow back on? I could barely get it over the rubber gasket, it took me longer than the sensors.

[632 Regal]

the 540 uses an aluminum elbow, the 530 uses a plastic one. WHen I work on mine and loosen the air cleaner I have no problems at all where if I imagine an aluminum one without loosening the airbox I could forsee probs. Make sure everything is still connected good when done.


Thanks guys, easy as can be. I also found that the throttle body elbow was half off, which is scary, so I took the opportunity to clean the throttle body and ICV. I also did the ECU reset. Runs smooth now, with no CEL, I'm happy.

An aside, is it supposed to be a bitch to fit that TB elbow back on? I could barely get it over the rubber gasket, it took me longer than the sensors.