[x300] X300 - Oxygen Sensors

I have been really interested in the subject of oxygen sensors and this has prompted me to look at
various internet sites. It appears they only have a useful service life of between 30,000 and
50,000 miles when they should be replaced.

It has never occurred to me to replace my sensors before but if they do (very
understandably)deteriorate with usage, then it would make sense to replace them and perhaps gain
better idling and mpg returns.

Three questions therefore. I see the USA site a lister recently recommended has them for $99
each. Is that cheap? Second, given the harsh environment they are in, ie extreme heat and rust,
are they a pig to remove, bearing in mind that they are probably in a pretty inaccessible
location? And third, is it correct that UK models only require two sensors whereas North American
versions had four? If so, why the difference?

Steven Corbett________________________________________________________________________
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  1. I bought all four O2’s from the site you mentioned for $400. Yes this is
    considered cheap since the dealer wants $492 USD for just ONE. Also keep in
    mind that the sensor the Jaguar uses is only installed in two percent of ALL
    the cars that use an oxygen sensor. It is a titania resistive sensor versus
    being a Zirconia sensor. DO NOT SUBSTITUTE ONE FOR THE OTHER! It won’t work.
    An easy way to tell Titania sensors is that two of the four wires are Yellow
    and Red.

  2. I had my independent do the work on removal of the old ones and refitting
    the new ones. I can imagine removing the original sensors may be a pain. It
    is IMPERATIVE that when you refit the new sensors that each individual
    sensor is wired to it’s original wiring harness. DO NOT CONNECT SENSORS TO
    OTHER o2 WIRING HARNESSES. One way to make sure that this is done properly
    is replace ONE SENSOR at a time. If you replace the sensors with no regard
    to how they were originally wired you will have SERIOUS PROBLEMS and will
    have to take your car to a dealer to have the ECU re programmed. NOT COOL!

  3. I can only speak for certain about the US market having four sensors, but
    from what I have read the ROTW (rest of the world) has two sensors.

Difference is that the US needs monitoring of what is going into the
Catalysts and what is coming out post catalysts. Kind of like a mini “smog
test” as the car is running.

P.S. These things are VERY FRAGILE. If you drop them, they might be
inoperative. Treat them better than a spark plug an you will be ok.

Tim
1995 XJR> From: Corbetts corbetts13@btinternet.com

Date: Tue, 2 Mar 2004 11:06:56 +0000 (GMT)
To: x300@jag-lovers.org
Subject: [x300] X300 - Oxygen Sensors

I have been really interested in the subject of oxygen sensors and this has
prompted me to look at
various internet sites. It appears they only have a useful service life of
between 30,000 and
50,000 miles when they should be replaced.

It has never occurred to me to replace my sensors before but if they do (very
understandably)deteriorate with usage, then it would make sense to replace
them and perhaps gain
better idling and mpg returns.

Three questions therefore. I see the USA site a lister recently recommended
has them for $99
each. Is that cheap? Second, given the harsh environment they are in, ie
extreme heat and rust,
are they a pig to remove, bearing in mind that they are probably in a pretty
inaccessible
location? And third, is it correct that UK models only require two sensors
whereas North American
versions had four? If so, why the difference?

Steven Corbett


Yahoo! Messenger - Communicate instantly…“Ping”
your friends today! Download Messenger Now
http://uk.messenger.yahoo.com/download/index.html

In reply to a message from Corbetts sent Tue 2 Mar 2004:

Replacing original sensors is usually not difficult, since they are
installed with plenty of anti-seize and should come out without any
special difficulty. I always warm the exhaust up which helps with
the removal. The Jag sensors are easy to get to if you can get
under the car. Be sure that the new threads are well coated with
proper anti-seize (this means conductive). If you have a frozen
one, apply some Aerokroil or other high-end professional polymer
penetrant (the usual parts store stuff is much less effective) and
wait a few minutes. If it is still stuck, put a torch on the pipe
area around it and cook it good, but don’t burn down the car, make
some heat shields from heavy aluminum foil or sheet metal. I just
hate to give easy work like this to shops but there is always that.–
The original message included these comments:

each. Is that cheap? Second, given the harsh environment they are in, ie extreme heat and rust,
are they a pig to remove, bearing in mind that they are probably in a pretty inaccessible


Brian Caro
Newport News, VA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Corbetts sent Tue 2 Mar 2004:

I also have a question on the O2 sensors. Mine are original with
133K miles on them. I have never had a check engine light, and my
car runs very well. I have noted of late that my mileage is down a
bit, maybe 1.5 MPG across the board.
Is there any way to measure the deterioration, if any, of my O2
sensors? Any way to isolate which specific sensor is deficient?
I have a US version with 4 sensors.–
uncle
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from uncle sent Tue 2 Mar 2004:

A story about my Volvo might be informative at this time:

My venerable 1987 240DL has 487,000km (304,000 miles) and is
equipped with its original O2 sensor (I am original owner). When my
mileage began to suffer very badly in the fall, I suspected the o2
sensor since I could not believe it would last this long. It is a
Bosch (heated) two or three? wire sensor so it is different to the
X300’s. At one point over a year ago, another member of this list
gave me the resistance value for this particular sensor, not quite
believing it could last this long as well. As part of my many
faceted search for an explanation, I decided to clean up my sensor
with a propane torch as per an idea I found on the internet. Since
I assSumed it was a goner anyway, I made a very liberal application
of fire and brimstone to ensure that I did a thorough job since my
intention was to replace it anyway. The tip was read hot. After
reinstalling it (it was cool), I measured the resistance and found
it still within range but on the low side (they apparently
deteriorate slowly over time). Evidently, cleaning the sensor did
not correct my poor gas mileage (approx 25% less than normal).
After a number of shadetree attempts at debugging the problem, I
capitulated the vehicle to the local garage which identified the
problem as a defective fuel pressure regulator. After the regulator
was replaced, the car past the emissions test with flying colours.

My own personal conclusions and thoughts: Bosch 02 sensors can
last a very, very long time and 02 sensors can be contaminated by
fuel high in sulfur or additives such as MMT.If a normally
aspirated AJ16 engine does not achieve about 25 miles per imperial
gallon on the highway (about 21 miles per US gallon) at a steady
speed around 100 kmh (62 mph) with tires above 30 psi, ambient
temperature about 21 Celcius (~70 F) with wind not a major factor,
it is achieving less than normal MPG.–
The original message included these comments:

I also have a question on the O2 sensors. Mine are original with
133K miles on them. I have never had a check engine light, and my
car runs very well. I have noted of late that my mileage is down a
bit, maybe 1.5 MPG across the board.


Dave J 1996 XJ6 (Canada)
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Corbetts sent Tue 2 Mar 2004:

$99.99 USD United States Dollars

= �54.3263 GBP United Kingdom Pounds

1 USD = 0.543317 GBP 1 GBP = 1.84055 USD

Thats cheap :-))

U.K Jag Dealers �250ea approx

Motor Factors �150ea + VAT

Derek
95 XJR
U.K–
Del Boy
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Hi,

I am pretty sure the OBDII Spec also includes real time oxygen sensor
monitoring.

What you can do is go to the dealer or independent specialist and ask them
to hook up their magic gizmo to the OBDII test port under your dash. There
should be a parameter in the device to measure individual O2 readings as you
are driving/idling to see what’s up.

With 133,000 miles you are past the design life of the parts anyway, so it
may be an idea to replace them.

Tim
1995 XJR> From: “uncle” dbernard@qts-inc.com

Date: Tue, 2 Mar 2004 16:11:41 +0100
To: x300@jag-lovers.org
Subject: Re: [x300] X300 - Oxygen Sensors

In reply to a message from Corbetts sent Tue 2 Mar 2004:

I also have a question on the O2 sensors. Mine are original with
133K miles on them. I have never had a check engine light, and my
car runs very well. I have noted of late that my mileage is down a
bit, maybe 1.5 MPG across the board.
Is there any way to measure the deterioration, if any, of my O2
sensors? Any way to isolate which specific sensor is deficient?
I have a US version with 4 sensors.

uncle
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Timothy M. Sheehan sent Tue 2 Mar 2004:

Hello all,

I was dealing with o2 sensors for a last 2 years and I have no clue
how working o2 sensor can improve performance and solve problem
with gas consumption.
First - in US models only rear sensors responsible for fuel
cocktail.
So there is no reason to even touch front sensors.
Second - each sensor cost 125 - so for 2 of them minimum that you
will pay it’s 250. For 250 you drive and drive and drive until you
will get balance.
Third - the reason why is o2 sensors so expensive that they are
made from platinum or may be made of different expensive metals
only to last for a long time - o2 sensor should last for a life of
your car easy. May be Jaguar sensors were badly design and that is
reason why your sensors can fail. But failure may happen not only
to sensor but also to heater part - because modern sensors are
heated - that is why they have 4 wires.
And sensor sends signal to ECU - signal in ohm - I don’t remember
digits but it doesn’t matter. Its sends signal depends of how reach
is your mixture in exhaust and ECU corrects how much oxygen or gas
to send by injectors. So I find hardly to believe that changing
working o2 sensor to another working sensor will improve something.
Get obd2 reader - plug it in and drive and see how your o2 sensor
reacts to the acceleration.
Of course you can check o2 sensor and see they may be dirty and you
can try gently to clean them up but you should not feel difference
in driving.

That is just my opinion from my experience.
I may be wrong - correct me then–
Alex
Lake Bluff, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Hi,

First a working O2 sensor improves performance because it works. It is the
faulty ones that cause the problems.

You are incorrect regarding the rear sensor operation. Why would there be
two upstream sensors fitted if they weren’t there to equalize the other two.

The first two are the baseline readers. They sniff the exhaust directly out
of the motor.

The two after the cats sniff the exhaust after it exits the cats. With this
info the ECU then adjusts the mixture based on the readings of the O2’s.
There is something at work here called the stoichiometric ratio, which is
the ideal mixture of 14.7:1 air to fuel (by weight) for gasoline.

This is where the O2 readings come into play. Without proper readings from
the sensors, the ECU can’t get as close to that ratio as possible, and your
car runs RICH or it runs LEAN (bad for XJR’s)

Wrong on the price. I got 4 sensors for my XJR which are identical to XJ6
sensors for 100 USD a piece. Don’t forget that by replacing O2 sensors you
are not just saving on gas consumption you are also saving on cylinder wear
and oil changes as a rich mixture washes the oil off the cylinder walls, and
if you do oil analysis a better running car allows extended oil drains. It
all adds up. Not to mention the time out of your day having to stop for gas
more, etc, etc.

It’s also not true that the O2 sensor should last the life of the car. Why
are there vehicles out there that turn on the check engine light just
because the car has gone 50,000 miles?

Also the signal from the O2 sensors is measured in volts. I’m not sure if
most of you know but the oxygen sensors equipped in our X300’s are not run
of the mill O2’s They are used in only 2 percent of the cars made that use
oxygen sensors. They are of the resistive variety, and use a titania (not my
word) element rather than a zirconia element. You mentioned platinum, but
this precious metal was mostly used in CATALYTIC CONVERTERS, hence their
expensive nature as well.

In the last paragraph you mention “So I find hardly to believe that changing
working o2 sensor to another working sensor will improve something.”

I don’t understand why someone would switch out working sensors for working
sensors and expect an improvement. I will say in confidence that a car with
over 50 to 70 thousand miles is due for O2 sensor replacement. Regardless if
the dash Check Engine light comes on. Most of us here change out our spark
plugs at scheduled intervals, correct? Why should the O2 sensor be any
different?

Tim
1995 XJR> From: “AGIMELMAN” agimelman@HoTMaiL.com

Date: Wed, 3 Mar 2004 00:08:32 +0100
To: x300@jag-lovers.org
Subject: Re: [x300] X300 - Oxygen Sensors

In reply to a message from Timothy M. Sheehan sent Tue 2 Mar 2004:

Hello all,

I was dealing with o2 sensors for a last 2 years and I have no clue
how working o2 sensor can improve performance and solve problem
with gas consumption.
First - in US models only rear sensors responsible for fuel
cocktail.
So there is no reason to even touch front sensors.
Second - each sensor cost 125 - so for 2 of them minimum that you
will pay it’s 250. For 250 you drive and drive and drive until you
will get balance.
Third - the reason why is o2 sensors so expensive that they are
made from platinum or may be made of different expensive metals
only to last for a long time - o2 sensor should last for a life of
your car easy. May be Jaguar sensors were badly design and that is
reason why your sensors can fail. But failure may happen not only
to sensor but also to heater part - because modern sensors are
heated - that is why they have 4 wires.
And sensor sends signal to ECU - signal in ohm - I don’t remember
digits but it doesn’t matter. Its sends signal depends of how reach
is your mixture in exhaust and ECU corrects how much oxygen or gas
to send by injectors. So I find hardly to believe that changing
working o2 sensor to another working sensor will improve something.
Get obd2 reader - plug it in and drive and see how your o2 sensor
reacts to the acceleration.
Of course you can check o2 sensor and see they may be dirty and you
can try gently to clean them up but you should not feel difference
in driving.

That is just my opinion from my experience.
I may be wrong - correct me then


Alex
Lake Bluff, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Timothy M. Sheehan sent Wed 3 Mar 2004:

Don’t get me wrong. I was under imression that you changed 4
sensors just to renivew them as we do for spark plugs.
Here is good link about o2 sensors.
Just keep in mind that modern sensors last much longer and no need
to replace them as spark plugs for sure.

http://hostingprod.com/@aa1car.com/library/o2sensor.htm--
Alex
Lake Bluff, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

No worries.

I had one faulty sensor, and I replaced all four seeing as the other three
were probably on their way out too.

Tim
1995 XJR> From: “AGIMELMAN” agimelman@HoTMaiL.com

Date: Wed, 3 Mar 2004 02:25:43 +0100
To: x300@jag-lovers.org
Subject: Re: [x300] X300 - Oxygen Sensors

In reply to a message from Timothy M. Sheehan sent Wed 3 Mar 2004:

Don’t get me wrong. I was under imression that you changed 4
sensors just to renivew them as we do for spark plugs.
Here is good link about o2 sensors.
Just keep in mind that modern sensors last much longer and no need
to replace them as spark plugs for sure.

http://hostingprod.com/@aa1car.com/library/o2sensor.htm

Alex
Lake Bluff, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Corbetts sent Tue 2 Mar 2004:

Hi

I had to buy one of those lamda sensors due to road accident.
( engine was running rich, about 5 extra liters / 100km

  • CO2 was sky high 8% )
    Only place to get them was jaguar dealer. Keep your thumbs-up,
    that you dont have to replace them, price was 600 euros each.

Regards Teppo Finland Europe–
honda78
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Alex,

On OBD II certified engines, the manipulation of oxygen sensor signals is quite complex. Normally, the forward mounted (prior to catalytic converter) sensor is the primary sensor for controlling air-to-fuel ratio. The rear mounted sensor is used to check the operation / efficiency of the catalytic converter (by signal comparison) and to serve as a secondary backup to the front sensor in case of failure. The rear mounted sensor is also involved with controlling air-to-fuel ratio, just not to the level as the front sensor.

“Modern” oxygen sensors, as used in typical OBDII (and OBDI systems), have an indefinite operating life. From a theoretical perspective, they do NOT wear out. Of course, with any electro-mechanical device used in such a difficult environment, it can fail from thermal fatigue or mechanical vibration … or even impact with road debris. Manufacturers do NOT currently list a replacement interval for these components. Instead, they allow the onboard diagnostics features within the engine ECU to inform the owner as to any malfunction. Its my understanding, but I do not know this to be a fact in all applications, that the diagnostic section in modern engine ECUs can every monitor “rate of change” characteristics for O2 sensor which provides for the ability to “determine” a lazy sensor. If you think about it, this is an elegant solution as it is far more precise and cost effective versus an arbitrary mileage interval. It is true that very old designs had a specified replacem
ent interval, but this was due to the inability to monitor the sensor as the engine management system were quite primative as compared to contemporary designs.

Of the two types of oxygen sensors available (zirconium dioxide and titanium dioxide), zirconium is by far the most widely used. It’s found in approximately 80-85% of vehicles and it is the voltage generating type. The titanium design is a resistive type linking oxygen level to a change in sensor resistance. The X300 uses the titanium design … but other Jaguars do not. A faulty oxygen sensor can cost an owner a loss in fuel efficiency (if it fails rich) of approximately 10%. The oxygen sensor does not totally control air-to-fuel ratio as the primary parameters are set within the engine ECU operating characteristics. The sensor is best described as a fine tuning circuit. Of course, this fine tuning is absolutely necessary to maintain catalytic converter operation and meet emission standards.

Oxygen sensors are very important to the operation of modern vehicles. In my opinion, which seems to be strongly supported by all auto manufacturers, arbitrary replacement of these devices at some mileage interval is not required … nor is it beneficial in most cases. However, if you have some reason to strongly suspect a malfunctioning oxygen sensor, replace it if you so desire. On most modern vehicles, the cost of these sensors is NOT insignficant so you want to be sure of your diagnosis before you take these steps.

John P.

In reply to a message from Timothy M. Sheehan sent Wed 3 Mar 2004:

I guess the ultimate test would be to put back in the 3 that were
still good and see what the results were. I had a 1995 Nissan
240SX that had only one O2 sensor and it was cheap so I replaced it
at 100,000 miles just for fun. Noticed absolutely no difference in
performance or mileage.

Rick.
1995 X300 99,000 miles
(Original O2 sensors and 18 mpg stop and go city, 23 mpg highway)–
The original message included these comments:

I had one faulty sensor, and I replaced all four seeing as the other three
were probably on their way out too.


Rick D.
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from Rick D. sent Wed 3 Mar 2004:

If you car doesn’t run lean or reach there is no point to even
touch o2 sensors. Jaguar sensors is cost around $500.
Interesting this is that the have 4 different versions but all 4
sensors absolutely the same.–
Alex
Lake Bluff, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Dear All,

As any one with an X308 approaching 100 miles, I ran into O2 sensor issues.

To summarize:

  • P1646 is the pre-cat O2 sensor on bank 1 i.e. the RIGHT hand side of the car (looking forward from the driver seat);
  • P1647 is the pre-cat O2 sensor on bank 2 i.e. the LEFT hand side of the car;

I have purchased new O2 sensors on eBay (not the dirt cheap ones from China but 50 GBP ones from UK vendors) which people guaranteed where XJ8 compatible… to no luck (I tried two vendors and had to return them each time).

Eventually, I bought a Denso sensor, still on eBay from a seller by the name of “worldcarparts_uk” and paid 90 GBP for the sensor, still one third of the price at the Jaguar dealer! The company is
Oxflow Ltd
Tenby Units
Langrick Road
New York, Lincoln
Lincolnshire LN4 4YD - UK

The seller promptly informed me that the new Denso sensors are marked differently than the original ones: “Denso Q-E608” instead of “192400-3100” by that they were genuine Denso and fully compatible. And this time it worked perfectly.

So, in short, for XJ8 with the AJ27 engine we can use the Denso Q-E608 O2 sensors which come in a box marked DOX-0430 and save a bundle.

As for the work, one bank is very easy (the bank 1/ RH sensor on left hand drive cars). The other bank can be a nightmare if the heat shield bolted on the catalyser has Torx screws (apparently the standard on AJ27). I had to make a custom tool to remove the three damned screws! Other than that, make sure that you plug back the two small black plastic pipes in the right locations on the coolant filler - it is unnatural: the pipes must cross!

I hope this helps.