I bought a 1994 BMW 530i last October and have been giving a slow refresh ever since. I did all the fluids first and just got done with the shocks/struts. I've been trying to decide if I should change out the O2 sensors. I've seen everything from don't bother until they die to ever 30k no matter what. The car is about to turn over 160k and the sensors seem to be going okay but I have no way to tell how old they are or even really what condition they are in.
How often do you change O2 sensors?
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O2 sensor is not a scheduled maintenance item, replace it only when it failed. I didn't replace the two upstream O2 sensors of my LS400 until it failed at around 230-235k miles, the two upstream O2 sensors of my E430 failed at 120k miles.
The same for catalytic converter, muffler and pipes, if they perform well leave it alone don't waste money replacing them.
The same for catalytic converter, muffler and pipes, if they perform well leave it alone don't waste money replacing them.
I do the fronts at 75-100k and the rears when they fail.
I have never seen a mfgr spec for 02 replacement.
The engine control computer will tell you when.
The engine control computer will tell you when.
Mine failed at 113K on the Tacoma. Let them go until they die.
If the car has over 100K and they are cheap and easy to get at i may do them, or..
If they are a real swine to get at e.g. ford 5.4 and its close to 100K and the pipe has to come down for some reason like a manifold stud job they are getting changed.
Wide bands get left until they have issues regardless, they are just too expensive to swap out as part of my neurotic maintenance plan.
This applies to my own cars not customers, they get left alone unless they have issues.
If they are a real swine to get at e.g. ford 5.4 and its close to 100K and the pipe has to come down for some reason like a manifold stud job they are getting changed.
Wide bands get left until they have issues regardless, they are just too expensive to swap out as part of my neurotic maintenance plan.
This applies to my own cars not customers, they get left alone unless they have issues.
I would change mine on the CR-V at 110k right now but they are expensive. $70 for Denso front, $203 for Denso rear! I'm going to wait for either a CEL, a significant dropoff in fuel mileage, or 200k, whatever comes first. I drive 50k a year so it won't be that long.
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I'll throw this out since it seems to figure into how some of you decide: they're cheap ($30 each IIRC), there's only two, they're really easy to get to.
Originally Posted By: SteveSRT8
I have never seen a mfgr spec for 02 replacement.
The E46 BMWs have a maintenance interval for the O2 sensors, 100,000 miles for the M54 and 120,000 miles for the M56 engines.
It may have been sooner for the E36 models.
I have never seen a mfgr spec for 02 replacement.
The E46 BMWs have a maintenance interval for the O2 sensors, 100,000 miles for the M54 and 120,000 miles for the M56 engines.
It may have been sooner for the E36 models.
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Until check engine light on ^^
as shanneba said usually 100,000 miles for bmw's, gas mileage usually drops as they age
I had a lazy front o2 sensor that I recently replaced. It made my Saturn Vue go into closed loop mode within 20 secs vs the miles of driving it took before. No CEL ever lit, no difference in driveability or MPG. Only $34 for an NGK at least.
edit: Vue is an '05 w/ 82k miles at the time
edit: Vue is an '05 w/ 82k miles at the time
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Originally Posted By: cmf
You can check the resistance of the O2 sensors and replace them when they are "out of spec". Waiting until a CEL is waiting a little too long IMO.
Absolute nonsense.
You can check the resistance of the O2 sensors and replace them when they are "out of spec". Waiting until a CEL is waiting a little too long IMO.
Absolute nonsense.
The A1 & A2 GTIs had a 60K mile change interval (regardless of function) right in the owner's manual maintenance section.
It may have been overkill, or easy, profitable business for the dealers, but it was right there in the book.
It may have been overkill, or easy, profitable business for the dealers, but it was right there in the book.
Originally Posted By: mechtech2
Originally Posted By: cmf
You can check the resistance of the O2 sensors and replace them when they are "out of spec". Waiting until a CEL is waiting a little too long IMO.
Absolute nonsense.
Yeah, multi-billion dollar manufacturer's put "absolute nonsense" for their recommendations for testing heated oxygen sensors.
I found this part of a Toyota repair manual online. You should call them and tell them how they put "absolute nonsense" in their repair manuals. Hyundai actually lists resistance as the only diagnostic test to perform on oxygen sensors.
http://highlanderclub.ru/files/manual/04/21j6774i/cip0037.pdf
1 INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Disconnect the H10 or H6 heated oxygen sensor connector.
(b) Check the resistance of the heated oxygen sensor terminals.
Originally Posted By: cmf
You can check the resistance of the O2 sensors and replace them when they are "out of spec". Waiting until a CEL is waiting a little too long IMO.
Absolute nonsense.
Yeah, multi-billion dollar manufacturer's put "absolute nonsense" for their recommendations for testing heated oxygen sensors.
I found this part of a Toyota repair manual online. You should call them and tell them how they put "absolute nonsense" in their repair manuals. Hyundai actually lists resistance as the only diagnostic test to perform on oxygen sensors.
http://highlanderclub.ru/files/manual/04/21j6774i/cip0037.pdf
1 INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Disconnect the H10 or H6 heated oxygen sensor connector.
(b) Check the resistance of the heated oxygen sensor terminals.
They are having you check the resistance of the heater coils, not the O2 sensor itself. It isnt a way to tell if the O2 sensor itself has failed. If the heater coils fail the O2 will continue to function, however it will take longer for them to warm up and begin working. This will often result in a CEL because it will take longer than the PCM is expecting.
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