Unscrewing existing LAMBDA sensor

bxman · Unread post by **bxman** » 01 Jan 2009, 19:39

I would like to change the sensor, if possible without having to remove the exhaust system. On this particular car it is directly above the steering ram and horizontal and parallel with it. I have had a pipe or claw spanner on it but there is no way that I can I get more than 15 degrees of travel on the spanner , The most potential movement is in line with the exhaust pipe itself where needless to say it is difficult to get very much purchase.
I am reluctant to cut the wires even then I would need a deep socket to fit over the sensor.
Has anyone had the same problem and resolved it successfully.
Thanks to all in hopeful anticipation.
What happens if I cut the leads and still cannot get it out.
Will the engine still run?

16valve SX Mk1 P reg

citronut · Unread post by **citronut** » 01 Jan 2009, 19:44

can you unplug the sensor from the loom and put the plug conector through a ring sppaner, and the over the sensor

regards malcolm

AndersDK · Unread post by **AndersDK** » 01 Jan 2009, 20:06

If you cut the wires, the engine management system will behave like the Lambda sonde is still cold.
That will set off the management fault lamp at some time after warm up of the engine, as the system senses the engine temp rises.

It will also tend to raise the temp in the cat, as there is then no management controlling loop to control any excess fuel in the exhaust.
In long terms it will harm the cat as it will simply burn out.

In short terms over a couple of days nothing happens. Meaning you have lots of time fitting a new lambda sonde if that the route you choose.
Lambda sondes are not that dear anymore as aftermarket parts - £30 tops - or you've found the wrong dealer.
They comes as standard parts for PSA's in different generations. You need a 1.st generation 4-lead PSA style, which happens to be one of the most common types.

Have a poke in tool markets as there are speciel sockets available especially for this job. They have a slot to clear the wiring connectors from the sonde. They have also come down in prices over the last years.
Certainly cheaper than a new sonde.
usually you will only find one size. They fit the sonde you have on your Xantia

Just follow the wiring backwards up into the engine bay, and you will find 2 connectors somewhere.
The wiring and connectors are quite sturdy to endure the heat from the exhaust, so they should survive some messing around.

bxman · Unread post by **bxman** » 01 Jan 2009, 21:30

Thanks folks
Ii is not the normal PSA plug that you can undo
It's a substantial 4 way plug about 27/28 mm across and 3or4 wide
it will not pass through a 22mm ring.

andycarter · Unread post by **andycarter** » 02 Jan 2009, 08:20

bxman wrote: I am reluctant to cut the wires even then I would need a deep socket to fit over the sensor.

This special socket might be just what you need:
http://www.cromwell.co.uk/KEN5032760K

citronut · Unread post by **citronut** » 02 Jan 2009, 09:01

as long as you make a note of the order of the pins in the plug, you sould be able to remove the pins from the plug body, then they will pass through the sppaner

regards malcolm

AndersDK · Unread post by **AndersDK** » 02 Jan 2009, 22:34

citronut wrote:as long as you make a note of the order of the pins in the plug, you sould be able to remove the pins from the plug body, then they will pass through the sppaner

regards malcolm

Good idea Malcolm.

2 of the 4 wires would have the same colour. These wires are the heater in the lambda sonde, and they dont need to be in any specific order. They simply carry a +12V feed and chassis earth.

leaving you with only 2 wires to manage ...

bxman · Unread post by **bxman** » 04 Jan 2009, 21:51

Me again.
Yes you do need the special socket.

There is no means of extracting the pins from the socket.
the wires are molded in on all of the 3 sensor's that I have come across.

So I cut the wires shortened them twice only to find that even after removing them completely a regular deep socket was
not long enough for the sonde that was fitted.

when it came to reconnecting the plug
Then I found out that there is a black and a white plug.
They are identical except that they have a different key so are presumably made with different characteristics.
Does Anyone KNOW are the sensors ECU specific ?

I have now managed to source another with the white plug and hope to finish the job in the morning.
Given the choice of down pipes go for one with the sensor at 1,30 -2,30
not one at 3'oclock as it makes live a lot easier.
Most grateful to everyone that has contributed.
Thanks Patrick

16v 1.8 SX dual fuel

citronut · Unread post by **citronut** » 04 Jan 2009, 23:57

it is best to buy a new lambda sensor with a generic plug factory fitted, as this will remove any faults with bad conections, as the wires are stainless steel so hard to make a sound conection

regards malcolm

MikeT · Unread post by **MikeT** » 05 Jan 2009, 16:23

bxman wrote:Does Anyone KNOW are the sensors ECU specific ?

Narrowband (AFR) sensors are generic though there are different types which I reference as 2, 3, 4 and 5 wire. You may have to splice into your loom/connector if they don't have the right fitment but do the job.

A word of warning though, there are some "fake" sensors made that do not sense at all, they just emit the "right signal" to keep the ECU happy.

citronut · Unread post by **citronut** » 05 Jan 2009, 18:37

it is fare better to buy a O/E or generic sensor this saves any hit and miss to if it works or not, look up a company called FUEL PARTS, theyt are very helpfull if you require any info, my local factors supplie there equipment, we had a problem sortting a lambda sensor out, so my factors gave me the contact number and they were very good

here is there link

http://www.fuelparts.co.uk/

regards malcolm

bxman · Unread post by **bxman** » 05 Jan 2009, 21:22

Hi Mike
Thanks for the info. Jim has recently put up 4 different circuits for different ECU's used on the XU7JP4 engine.
And I suspect there may be even more out there ??
Each one has a different loom associated with that particular ECU.
from what I can see they all interface with the same devices.

I spent an hour this morning looking at lambdasensor.co.uk studying the plugs used on the 16 valve XUxxx family.
Of the 16valve's Citroen's listed there were 12 different sensors with 5 plug types, 11 of them being 4 wire devices the other a 5 wire.

As far as I can see the white plug on mine with the Sagem SL96-1 is the type 82 connector
and the black plug connector type 49 mated up with a Bosch MP5.1

I feel that with stainless steel wires being used it must be preferable to get a compatible plug for the existing loom rather
than crimping wires together.

Oh how complicated life is made for us tying to keep our motors going on a shoestring!
At least my beast run sweeter, again this morning, than it has done for a while. Fingers crossed as I have thought that I had
effected a cure before only to be disappointed a day or so later.

dual fuel SX 1.8 Xantia

MikeT · Unread post by **MikeT** » 06 Jan 2009, 13:38

Isn't it typical of manufacturers to try and make a generic product proprietary

though I'm all for improvement.

Looking at that lambda site they too advocate the use of universal sensors and splicing into your wiring though I'm not sure why there's a year date limitation to the zirconia type, appears to be differing heater elements? Oh well, that's progress for you.

I hope it all goes well whatever you decide.

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Unscrewing existing LAMBDA sensor

Unscrewing existing LAMBDA sensor

Re: Unscrewing existing LAMBDA sensor