Yellow Engine Light - Engine Diagnostics

Gregg1100 · Unread post by **Gregg1100** » 09 Mar 2006, 16:16

Hi,
My yellow light stays on for a few seconds now, sfter engine has started. I think that you used to be able to void any faults by disconnecting battery overnight, is that still true ?. The system has to re-learn the settings again, once battery re-connected.
Greg

cosb6 · Unread post by **cosb6** » 10 Mar 2006, 17:36

Right-e-o....

I've done more "net" research, and was wondering if someone, or more than one person, can confirm it DOES NOT NEED PROGRAMMING IN!....

If not, I can get the part direct from Bosch for £52.99 delivered... somewhat cheaper than the dealers who want 300% that price!!!!!!!

If it's a simple bolt on / plug in job I might as well do it myself!

wheeler · Unread post by **wheeler** » 10 Mar 2006, 19:27

AndersDK wrote:I'd say this is way too early for a Lambda probe to fail.

Are you joking ? i'v known loads of oxygen sensors to fail on citroens & peugeots at half that mileage

AndersDK · Unread post by **AndersDK** » 10 Mar 2006, 23:53

wheeler wrote:
AndersDK wrote:I'd say this is way too early for a Lambda probe to fail.
Are you joking ? i'v known loads of oxygen sensors to fail on citroens & peugeots at half that mileage

No joke -
A lambda sensor does not pop out like this. But anything that feels like failing will do so

- by Murphy's law.

cosb6 · Unread post by **cosb6** » 11 Mar 2006, 19:09

AndersDK wrote:No joke -
A lambda sensor does not pop out like this

I don't understand....

Anyway... the dealer say Upstream O2 sensor... so I'll try that myself I think. Just hope the £52,99 is well spent!

AndersDK · Unread post by **AndersDK** » 11 Mar 2006, 22:41

The Lambda sensor, or O2 sensor, or oxygene sensor, or cat sensor, is a very sturdy sensor type.
Its made to work in the burning hot exhaust gasses for many years. There is not really a "sensing element" in the sensor as the working principle is the ionisation of hot air (by degree of oxygene content) between 2 metallic surfaces.
The distance between these metallic surfaces is several mm to allow the hot exhaust gas flow and keep clean the surfaces.

Therefore the Lambda sensor is inherently durable and sturdy.

Mostly it will fail due to fulty cabling : ether cabling wrongly resting against the hot exhaust, or corroded cabling due to the road emvironment, or mechanical faults in connectors.

Blind tests by DK motoring clubs have shown that even mechanics removes the Lambda connector plugs and forgets to reconnect these during other service works in the shops ...

dty · Unread post by **dty** » 12 Mar 2006, 13:07

Hi it's me again with the light probelm and sorry to take it in another direction but the code reads P0906 on my Xsara HDI which states "Gate Select Position Circuit Low" - what does this actually mean and how do I remedy this?

cosb6 · Unread post by **cosb6** » 12 Mar 2006, 18:21

They might be durable, but I've measured the resistance of the heating element, and it's definatly knackered somewhere. I doubt it's been damaged as it went duff and the bonnet hadn't been up for about 6 weeks before (oops), so it was undisturbed....

Most failures might be wiring, I'll know when I take it apart, but for now a new sensor is going in. I'll leave the battery off for about 45 mins whilst I do the job, and we'll hope the dash light disapears afterwards.......

AndersDK · Unread post by **AndersDK** » 12 Mar 2006, 18:37

1) How do you know which 2 wires are the heater element on the lambda sensor ? I mean - if you DO know - then why not buy a cheaper aftermarket sensor and connect it as pr your knowledge ? - remaining 2 wires are not hard to guess the usage for ...

2) Heating element is only used during warm up of the sensor - not warm up of the engine !

cosb6 · Unread post by **cosb6** » 13 Mar 2006, 08:41

The 2 white wires are the element, and it should have about 6 ohms resistance.... which is exactly what the 2nd sensor is doing.....

The front one is pretty well open circuit, with v-high resistance and accoring to "www.lambdapower.co.uk" the only fix for this is a replacement sensor.

It can't be a broken wire (it's not completely open circuit), so I don't know what it is....

Until last Wednesday I didn't know anything about the sensors, so using a universal one might not work. Apparently, not all universal ones will be 6 ohms (that might just be citroen) so buying the part from Lambda power gets me the exact correct part.....

I just need a Citroen Guru to confirm leaving the battery off for 45mins will reset everything nicely....... I don't want to have to go to a dealers anyway.....

AndersDK · Unread post by **AndersDK** » 13 Mar 2006, 11:29

Citroen has not decided for a 6 ohms heater element

Thats just the wattage - or time delay in other words - before the initially cold Lambda sensor witll start producing sensible data.
After the first few minutes the Lambda sensor is self containing by the exhaust heat.

Anyway - my point is (and was) to try save you money by forcing you to investigate the problem a bit deeper - which you now have done diagnosing the problem.
And of course I do agree a Lambda sensor no working pre-hetaer is a piece of crap.

- I was just wondering how I could convince you saving even more £'s explaining the Lambda sensor is not a special Citroen patented device 8)

cosb6 · Unread post by **cosb6** » 13 Mar 2006, 11:40

Hi.. and thanks..

No I agree, a sensor is just a sensor... I've just read on some cars they can be sensitive enough to know if it's the genuine article or a Universal one.... but that doesn't apply to Citroens (as far as I know)...

Also, the cheapest Universal one I've found is £45, so to pay an extra £7 for the genuine part seems a good deal. True though, it would be cheaper, and I agree that the Xsara Sensor is just a sensor, where any one would do.....

Thanks for the advise anyway. Can you confirm about leaving the battery disconnected / the Engine Light Resetting itself?

AndersDK · Unread post by **AndersDK** » 13 Mar 2006, 11:48

Errmhhh...

The reset bit I'm not sure on - but removing battery connection for an hour wont cost you anything

- provided you have your radio & any key code stored !

cosb6 · Unread post by **cosb6** » 13 Mar 2006, 13:04

Got a Key Code, but thats for getting new keys cut (i presume)... don't think the radio has one.... it's custom fit, so I wouldn't see the point in it having one.......

It's got everything the previous owner had... so should be fine....

cosb6 · Unread post by **cosb6** » 13 Mar 2006, 14:13

Should I have a radio code?

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Yellow Engine Light - Engine Diagnostics

Yellow Engine Light - Engine Diagnostics

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