Code PO430

[abertawe1970]

Hi please help me! I have a C5 3.0 V6 2002 which is now coming up with the error code PO430 Catalyst System Efficiency Below Threshold (Bank 2), the on-board computer is displaying ' Catalytic Converter Fault & Anti-pollution Fault'. The car runs fine but is a bit lumpy when cold, my question is where is the sensor and are they hard to change? To check the voltage first what is the correct volts I should be getting, also where would the wiring block be in the engine bay to check?

[Mandrake]

What makes you assume it's a sensor fault ?

The pre-cats on this engine do have a tendency to fail and are quite sensitive to being damaged by running with an ignition misfire, lumpy running could be due to a misfire.

Coils are renowned for failing on this engine too, although that would usually set its own fault code if a coil completely failed.

Do you have access to a Lexia or just a generic OBD-II reader ? There are a number of tests that can be run with a Lexia to test the oxygen sensors (there are four) and also test the condition of the pre-cats if you're willing to dig into it a bit...

Somewhere on here (not sure how to find it) are some good posts from Ben82 showing the Lexia diagnostics graphs for testing the oxygen sensors...

[myglaren]

Is this the thread you were referring to Simon?

[Ben82]

Is this the thread you were referring to Simon?

http://www.frenchcarforum.co.uk/forum/v ... 32#p357213" onclick="window.open(this.href);return false; It's this one

Though the image is missing... I'll see if I can find it, though finding an image called kittens on my laptop might be a bit difficult

[Mandrake]

It looks like ALL the picture attachments in that thread are missing, possibly due to the forum upgrade Pity, as it makes that thread very hard to follow with all the graphs and pictures missing...

[Ben82]

Well being the pack-rat that I am has paid off:


Mine does occasionally come up with the Anti Pollution fault with the P0420 and P0430 codes. And they will normally stick around for a while, I have cleared both via lexia, and am still on the same cats.

If I remember correctly (though I haven't changed them myself), the rear bank sensors are a real pain to get to.

I would first go for a lexia clear of the errors, and if they return, then do the graphing to attempt to judge whether it is the cat or the sensor.

[abertawe1970]

Only managed to get hold of a generic OBD-II reader to clear the faults, I do know someone with the lexia as well so will get them to look at it.
Cheers for all your advice guys.

[abertawe1970]

Quick update! Found that cylinder number 4 has a misfire and is now running on 5 pots only, how hard is it to get the inlet intake manifold off? Is there any destructions on here to help? Also which one is number 4?

[Mandrake]

Cylinders are numbered 1,2,3 on the front bank from the LEFT hand side of the car, and 4,5,6 on the rear bank also from the LEFT hand side.

So 4 will be on the rear bank on the left of the car. (Right looking into the engine bay from the front)

Hopefully Stempy will be along as I think he's had the inlet manifold out of his. Shouldn't be too hard - I've done the Xantia version of the V6 many times. You probably want to get a new gasket for the upper to lower manifold interface, even though I think it's a reusable rubber type on the ES9J4S instead of paper you might damage it getting the manifold out.

If you've no idea when the spark plugs were last changed I'd probably do them too as a misfire could potentially be a spark plug, so you don't want to be taking the manifold out twice...

It's not uncommon for the rear bank spark plugs to be neglected (never changed) in these even though the front ones have been changed because it's a manifold out job!

Don't drive the car too much (ideally not at all) and only with a light throttle until fixed because if it's an ignition misfire and fuel is still going into the cylinder it can quickly destroy one of the pre-cats due to raw fuel in the exhaust causing it to overheat, if that hasn't already happened.

[Ben82]

Here's the official Citroen docs on how to do it: https://mega.co.nz/#!E5Ng3LAC!F9dCZCEif ... Vb2JPc_bc4" onclick="window.open(this.href);return false;

[Mandrake]

Thanks Ben, very helpful!

It's really not a bad job, the hardest part is lifting out the intake manifold due to it being quite heavy (at least the one on the Xantia is as its all alloy) and avoiding the things that it wants to snag on, then lifting it back into place...

I think I've got it down to about half an hour to get it out now, but I would allow double that for someone who has never done it before.

I would also advise as soon as the inlet manifold proper is lifted out that the inlet runners should be blocked by gently stuffing a scrunched up piece of paper kitchen roll into each one - you REALLY don't want a nut or other foreign object falling into one the runners and passing through an open valve into a cylinder as that would be a major disaster.... Just remember to remove the kitchen roll pieces before refitting the manifold...

[Ben82]

I would also advise as soon as the inlet manifold proper is lifted out that the inlet runners should be blocked by gently stuffing a scrunched up piece of paper kitchen roll into each one - you REALLY don't want a nut or other foreign object falling into one the runners and passing through an open valve into a cylinder as that would be a major disaster.... Just remember to remove the kitchen roll pieces before refitting the manifold...

The doc does make a passing remark about this, though I think anyone could be forgiven for missing it.

Plug the air inlet openings.
.....
Unplug air intake orifices.

Forgot to say I think the bits in Figure: B1HP22TC is probably going to be the hardest thing to reach, as it's right at the back.

[abertawe1970]

UPDATE.
Can finally say that the beast lives again , it was the spark plug and coil on cylinder 4 that has caused all the issues,replaced the plugs and coil and cleared all error codes. Big thanks for everyone's help!

[Ben82]

UPDATE.
Can finally say that the beast lives again , it was the spark plug and coil on cylinder 4 that has caused all the issues,replaced the plugs and coil and cleared all error codes. Big thanks for everyone's help!

Excellent glad you got it sorted.

[abertawe1970]

Spoke too soon! Drove lovely yesterday but coming into work this morning the warning lights came on again , now I have:
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0172 Fuel Trim too Rich (Bank 1)
P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P0430 Catalyst System Efficiency Below Threshold (Bank 2)

I've changed all the plugs in 1/2/3 cylinders and set the gaps to 8000, and also changed the coil on cylinder 1.
Any ideas please