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Installing 02 sensors

I have a 2000 BMW 540i and I need new O2 sensors. How many do I need and what types. I have read online that there are upstream and downstream sensors. I would also like to know where they are located and how I can install them

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"Up-stream" means before the catalytic converters and are probably in the header pipe(s). The "down-stream" O2 sensors are behind the cats in the exhaust system, usually just behind them. Not the expert here on this particular car but there are probably 4 of these sensors. BMW exhaust systems are very tight on space, be careful tackling this job.

Posted on Jun 10, 2008

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Can an O2 oxygen sensor effect another sensor and give a false reading?


Check which side of your engine has cylinder #1. That side is bank 1. Bank 2 is the side opposite of bank 1. So bank 2 is not always passenger side. And since you seem to have extra O2 sensors, I would replace the other upstream and see what happens. Also the mass air sensor can give a trouble code issue to the upstream 02 sensors. Good luck. I've struggled thru this myself.

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To have a lean O2 Code --you could have a rich fuel
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Third you could have a failed O2 Sensor

Front or Upstream Oxygen Sensors get replaced at 100,000 miles

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My 1999 pontiac sunfire 2.2 liters did not pass the e-test. I feel that something tells my computer to run rich at 2000 rpm. I changed the spark plugs and the air filter. After driving 200 Klm. the engin...


The code P0137 means that your downstream O2 sensor has low volts. A rich running engine makes the voltage go high, not low. If the upstream sensor is not reading a rich or lean condition, then you need to replace your downstream O2 sensor.

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Dear sir/madam,i have jaguar 03 Xtype v6. my engine light is on and the code is p0430 can you please help me


P0430....Catalyst System Efficiency Below Threshold (Bank 2)try changing the O2 sensors the one before the cat is the first one to fail in normal circumstances ,must be an american market model this vehicle as i cannot read a europeon market vehcle here in europe ,encrypted software

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Engine light stays on after changing 02 sensor on my 2000 toyota tundra code read o2 sensor


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1 Answer

My 1995 525i has fault code 12210 O2 sensor message. I replaced sensor- same code. I unplugged new O2 sensor but left sensor engaged in exhaust pipe. I read the output and it was very lean. In this...


if the 02 sensor is unplugged and you are reading a scan tool from the diagnostic link then of course the 02 reading is wrong
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P0136, P1131, and P1151 codes on Ford Expedition 2000 4.6L


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I wouldn't spend the money to purchase 3 sensors. Highly unlikely all three are bad; Cost is about $40/ ea.
Since there isn't a code for the cat's themselves, I would suspect the O2 circuit is malfunctioning. The rough idle is another clue.


Take an ohmmeter set it on X10 scale and measure the resistance from engine to body and body to negative post on battery terminal. You should read zero ohms (full needle deflection). If you do go buy two upstream O2 sensors. If you read
open or a high resistance run two straps from eng. to body...and body to neg.batt. post.

FixYaWIZ................saailer

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Oxygen sensor (Only 1) located in exhaust system, on passenger side, below front seating area. countrycurt0

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