Are there 1 or 2 Oxygen sensors on the 535 ?

[Chad535]

Hi all,

A local repair shop diagnosis indicated a faulty O2 sensor on my 89 535. I bought the sensor, and while i was taking a look at the exhaust system i relaized that there seems to be another sensor right behind the Catalyst.....hmmm. I thought they only had one sensor there..i hope someone knows about it. one more thing is the message i get whenever i start the engine "CATALYST.....OWNER'S MANUAL"...the local dealer confirmed that it is caused by a bad O2 sensor, but with two of them now....i am a bit confused.

Thanks for your help.

[Black 535i]

..just ahead of the cat.

[Bill R.]

tempsensor after the cat that looks like an o2 sensor plus it has the o2 sensor in front of the cat... That seems to be the only market that shows up in the etk with the temp sensor though. That temp sensor will trigger a catalyst warning.







Hi all,

A local repair shop diagnosis indicated a faulty O2 sensor on my 89 535. I bought the sensor, and while i was taking a look at the exhaust system i relaized that there seems to be another sensor right behind the Catalyst.....hmmm. I thought they only had one sensor there..i hope someone knows about it. one more thing is the message i get whenever i start the engine "CATALYST.....OWNER'S MANUAL"...the local dealer confirmed that it is caused by a bad O2 sensor, but with two of them now....i am a bit confused.

Thanks for your help.

[Chad535]

Bill...... you are #1 ...it is a Japanese import. I have to check though if this sensor is available in the local market. However, i have one question.......what would be the use of a temp sensor behind the CAT ? ...Emissions control ?.

[Bill R.]

which case its not working...The reactions that take place in the cat generate some heat, and for example if you have a bad spark plug in a m60 and too much fuel doesn't get burned because that plugs not firing, then the unburn't gas ends up hitting the catalyst where it set off and generates much more heat than the cat should normally have.. if this happens for too long a period the cat can and will be damaged sometimes melting internally..so the temp sensor is there on that car to monitor that everthing is functioning normally.






Bill...... you are #1 ...it is a Japanese import. I have to check though if this sensor is available in the local market. However, i have one question.......what would be the use of a temp sensor behind the CAT ? ...Emissions control ?.

[Chad535]

Thanks Bill, the spark plugs have the normal color seen in a healthy engine, but still the O2 sensor error comes whenever a scanning tool is used for diagnosis, I think it is gone long ago. i need one more favor......do you know the normal resistance readings for the temp sensor ?....or any other way to test it ? it would be harder to verify if the CAT itself is damaged.

Thanks for your kind help

[Bill R.]

sensor, the us version doesn't use this and i suspect you'll have to get it from the japanese bmw manuals.





Thanks Bill, the spark plugs have the normal color seen in a healthy engine, but still the O2 sensor error comes whenever a scanning tool is used for diagnosis, I think it is gone long ago. i need one more favor......do you know the normal resistance readings for the temp sensor ?....or any other way to test it ? it would be harder to verify if the CAT itself is damaged.

Thanks for your kind help