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Thread: trouble codes
05-02-2011 02:03 PM #1
05-03-2011 11:25 AM #2
Oxygen Sensors - maybe the problem, maybe not.
Buy plug-and-play parts, too. Don't buy "generic" sensors and try to solder the wires - you will be for a world of woe. Most of the crap that they sell on eBay this way simply doesn't work. And the correct parts are not that expensive.
You will need a 22MM open end wrench or box end wrench, or you can buy the special tool from the parts catalog people. Both work, and I've used both.
The O2 sensors on this car are pretty cheap, as I recall - like $125 or so (as opposed to $250 for some other cars, such as the E36).
They are slated to be replaced at 100,000 miles, although they *may* last longer than that.
The P0420 and P0430 codes actually read "Catalytic Converter Efficiency Below Threshold" - but you are correct, it is likely an O2 sensor problem, not a Catalytic Converter problem (the latter rarely fails). The Primary O2 sensors, when they go bad, will run the car rich. You can reset the code (a code reader and reset tool and the Bentley manual are both highly recommended) and it will stay off for several months and then get worse with time.
There are also secondary sensors after the converter which sense the emissions - these can also go bad and trigger these codes.
The error codes are diagnostic tools and oftentimes, even though they mention a part in the code, the solution is not to change that part. For example, "Oxygen sensor out of range" is often an indication of a crack in the rubber intake elbow boot.
06-08-2011 03:22 PM #3
Curious to hear how the oxygen sensor replacement went, and whether this solved your problems. I have a 2001 X5 3.0 liter that has both the P0420 & P0430 codes. The first P0420 code was over a year ago, and was intermittent, so I didn't bother replacing it because I was able to pass inspection and get an inspection sticker. But now I've got both codes, and it's inspection time again.
07-27-2011 10:48 AM #4
Should fix the problem
The O2 sensors are slated to be replaced at 100,000 miles anyway. And they are fairly cheap, compared to older BMWs. I think I paid about $100 at Pelican.
A year later, no codes.
07-27-2011 12:40 PM #5
Perhaps I should figure out how to change them myself.
07-27-2011 04:37 PM #6
Try Primaries First
I replaced the primary sensors, as these control the fuel/air mixture. If the car has close to, or over 100,000 miles and these have not been replaced, you are not "wasting money" by replacing them.
If the code still pops up, I would try the secondaries next.
I would shy away from a mechanic who thinks there are three of then. On US spec cars, anyway, there are four - two primary and two secondary.
That being said, his price is reasonable for a mechanic - make sure he is using a quality part (no Chinese junk).
I just replaced the primaries.
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