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John E. Yurkon
Guest
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 Posted:
Mon Nov 15, 2004 5:40 pm Post subject:
cat bad? |
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A 1997 328is has had 5 fault codes in the past 145 hours of operation for
inadequate catalytic converter efficiency. The vehicle has 102Kmiles on it.
How accurate are the fault codes? The O2 sensors have never been changed.
Is there a chance that it's interpreting a week O2 sensors as poor converter
efficiency?
The dealer want's about $1,800 to change both cats.
John
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Fred W
Guest
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| Posted:
Mon Nov 15, 2004 5:40 pm Post subject:
Re: cat bad? |
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John E. Yurkon wrote:
| Quote: | A 1997 328is has had 5 fault codes in the past 145 hours of operation for
inadequate catalytic converter efficiency. The vehicle has 102Kmiles on it.
How accurate are the fault codes? The O2 sensors have never been changed.
Is there a chance that it's interpreting a week O2 sensors as poor converter
efficiency?
The dealer want's about $1,800 to change both cats.
John
|
The very first thing that I would do is put 4 new O2 sensors in it. You
are overdue for replacements anyway, and if you do need a new cat you
can transfer them to the new exhaust.
It is far more likely that one of the sensors is failing and that is the
reason for the error. Figure on about $100 each and you have two
upstream sensors and two downstream (after the cats). It is most likely
one of the downstream sensors that is causing that fault.
You could also bring the car to an emissions testing facility and for
the price of a test you could verfify that the cat is working before
shelling out megabucks on replacement cats.
-Fred W |
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Raybender
Guest
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| Posted:
Mon Nov 15, 2004 11:08 pm Post subject:
Re: cat bad? |
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"John E. Yurkon" wrote:
| Quote: | A 1997 328is has had 5 fault codes in the past 145 hours of operation for
inadequate catalytic converter efficiency. The vehicle has 102Kmiles on it.
How accurate are the fault codes? The O2 sensors have never been changed.
Is there a chance that it's interpreting a week O2 sensors as poor converter
efficiency?
The dealer want's about $1,800 to change both cats.
John
|
I don't directly know about the "accuracy" of the fault codes - however my Peake
Research Code reader has specific codes to test the O2 sensors vs the cat. This
is required because of the OBDII regs. Specifically, there are codes for
"lazyness" of each O2 sensor, codes for outright failure of any sensor or its
heater etc. Cat failure is detected by comparing the pre-cat and post-cat
sensor outputs as required by the OBDII regs.
So "it would seem" that the dealer "should" be giving you the straight scoop
here - you might want to get a second opinion, though. My 97 328 still has all
original O2 sensors and cats functioning just perfectly (I would guess - no
codes, anyway) at 115K miles, and I just passed CA smog a few months ago with
good margins.
Questions - do you do lots of "short trip" driving? Do you always use premium
grade fuel?
Frank
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John E. Yurkon
Guest
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| Posted:
Mon Nov 15, 2004 11:51 pm Post subject:
Re: cat bad? |
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"Raybender" <raybender@NOSPAMCovad.net> wrote in message
news:4198F0AB.3E8EB441@NOSPAMCovad.net...
| Quote: | I don't directly know about the "accuracy" of the fault codes - however my
Peake
Research Code reader has specific codes to test the O2 sensors vs the cat.
This
is required because of the OBDII regs. Specifically, there are codes for
"lazyness" of each O2 sensor, codes for outright failure of any sensor or
its
heater etc. Cat failure is detected by comparing the pre-cat and post-cat
sensor outputs as required by the OBDII regs.
|
If if compares the pre-cat and post-cat sensors and the post-cat sensor were
marginal
then couldn't it interpret this as a cat failure?
| Quote: |
So "it would seem" that the dealer "should" be giving you the straight
scoop
here - you might want to get a second opinion, though. My 97 328 still
has all
original O2 sensors and cats functioning just perfectly (I would guess -
no
codes, anyway) at 115K miles, and I just passed CA smog a few months ago
with
good margins.
Questions - do you do lots of "short trip" driving? Do you always use
premium
grade fuel?
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I always use premium and most of my driving is at least 6 miles but less
than 20 miles with three or four 300 mile trips per year.
John |
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Raybender
Guest
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| Posted:
Tue Nov 16, 2004 12:45 am Post subject:
Re: cat bad? |
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"John E. Yurkon" wrote:
| Quote: | "Raybender" <raybender@NOSPAMCovad.net> wrote in message
news:4198F0AB.3E8EB441@NOSPAMCovad.net...
I don't directly know about the "accuracy" of the fault codes - however my
Peake
Research Code reader has specific codes to test the O2 sensors vs the cat.
This
is required because of the OBDII regs. Specifically, there are codes for
"lazyness" of each O2 sensor, codes for outright failure of any sensor or
its
heater etc. Cat failure is detected by comparing the pre-cat and post-cat
sensor outputs as required by the OBDII regs.
If if compares the pre-cat and post-cat sensors and the post-cat sensor were
marginal
then couldn't it interpret this as a cat failure?
So "it would seem" that the dealer "should" be giving you the straight
scoop
here - you might want to get a second opinion, though. My 97 328 still
has all
original O2 sensors and cats functioning just perfectly (I would guess -
no
codes, anyway) at 115K miles, and I just passed CA smog a few months ago
with
good margins.
Questions - do you do lots of "short trip" driving? Do you always use
premium
grade fuel?
I always use premium and most of my driving is at least 6 miles but less
than 20 miles with three or four 300 mile trips per year.
John
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A marginal post-cat sensor should show up with a separate code compared to Cat
failure - at least if I understand the Peake Research instructions correctly.
Here's the list of codes involved with the Cats, and O2 sensors for 97 328.
Code Meaning
19 PreCat oxy sensor heater, cyl 1-3
2F Cat temp after startup
37 PreCat oxy sensor heater, cyl 4-6
3d AfterCat oxy sensor heater, cyl 4-6
4b PreCat oxy sensor voltage cyl 1-3
4c PreCat oxy sensor voltage cyl 4-6
4d AfterCat oxy sensor voltage cyl 1-3
4e AfterCat oxy sensor voltage cyl 4-6
4F AfterCat oxy sensor heater cyl 1-3
E3 Oxy sensor adaption limit cyl 1-3
E4 Oxy senosr adaption limit cyl 4-6
E5 PreCat oxy sensor response time cyl 1-3
E6 PreCat oxy sensor response time cyl 4-6
E7 PreCat oxy sensor switching time cyl 1-3
E8 PreCat oxy sensor switching time cyl 4-6
E9 Catalyst efficiency below threshold cyl 1-3
EA Catalyst efficiency below threshold cyl 4-6
Eb AfterCat oxy sensor heater power cyl 1-3
Ec AfterCat oxy sensor heater power cyl 1-4
Seems like a pretty comprehensive list that would discriminate between O2 sensor
failure vs cat failure. So it appears that the dealer is telling you he's
getting codes E9 & EA with none of the other above codes for oxy sensor
problems. Seems tough to screw up here unless somebody cannot read a chart -
though again you might just go get a second opinion, at another shop. It is a
lot of money.
One other long shot - take a 2-hour plus drive and spend significant time above
3K on the tach. Then get another read out of the codes, and be sure the engine
is hot (1/2 hour plus drive) when this is done. Easy for me to do here - just
go for a nice afternoon climb over the mountains - don't know how easy it is for
you. The idea is to see if getting the entire exhaust system up to temp and
holding it there for awhile might clean it out - but I don't know if cats can be
salvaged in this way.
Best luck
Frank |
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adder
Guest
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| Posted:
Tue Nov 16, 2004 2:22 pm Post subject:
Re: cat bad? |
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"John E. Yurkon" <yurkon@msu.edu> wrote in message news:<cnade8$rh$1@msunews.cl.msu.edu>...
| Quote: | A 1997 328is has had 5 fault codes in the past 145 hours of operation for
inadequate catalytic converter efficiency. The vehicle has 102Kmiles on it.
How accurate are the fault codes? The O2 sensors have never been changed.
Is there a chance that it's interpreting a week O2 sensors as poor converter
efficiency?
The dealer want's about $1,800 to change both cats.
John
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Buy a tester and test the O2 sensors? |
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John E. Yurkon
Guest
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| Posted:
Tue Nov 16, 2004 5:40 pm Post subject:
Re: cat bad? |
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"adder" <adder1969@yahoo.co.uk> wrote in message
news:66674363.0411160122.21c233cd@posting.google.com...
| Quote: | "John E. Yurkon" <yurkon@msu.edu> wrote in message
news:<cnade8$rh$1@msunews.cl.msu.edu>...
A 1997 328is has had 5 fault codes in the past 145 hours of operation
for
inadequate catalytic converter efficiency. The vehicle has 102Kmiles on
it.
How accurate are the fault codes? The O2 sensors have never been
changed.
Is there a chance that it's interpreting a week O2 sensors as poor
converter
efficiency?
The dealer want's about $1,800 to change both cats.
John
Buy a tester and test the O2 sensors?
|
That would be informative. But, considering the miles on the sensors I
should replace them anyway. The dealer SHOULD have an O2 sensor tester.
I'll ask them to test them after they replace them. If they don't have the
equipment, then I'll worry...
John |
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adder
Guest
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| Posted:
Wed Nov 17, 2004 2:51 pm Post subject:
Re: cat bad? |
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"John E. Yurkon" <yurkon@msu.edu> wrote in message news:<cnd2ee$2a05$1@msunews.cl.msu.edu>...
| Quote: |
That would be informative. But, considering the miles on the sensors I
should replace them anyway. The dealer SHOULD have an O2 sensor tester.
I'll ask them to test them after they replace them. If they don't have the
equipment, then I'll worry...
John
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It cost as much at a dealer for testing the O2 sensor as it did to buy
a new one when I had problems. BMW will say that any fault is
recorded in the car's computer. Sometimes it can be a bad connection
or broken wire. |
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