Citroen C3 - EGR Valve and engine diagnositcs

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Sat 21 Apr 2012 16:39
Citroen C3 - EGR Valve and engine diagnositcs - Talkingheads

Hi all,

I've got a 2004 Citroen C3 SX 1.4 HDi 92Bhp and had the engine light come on recently so took it in to the garage for diagnositcs.

Originally it returned four codes but they were not sure is these were old or new codes so reset the computer and told me to come back when the light came back on to see what was there. This happened so duly went back to the garage.

They returned the following codes:

P0401

P0400

P1351

There advice at this stage was that it must be the EGR valve and it would need replacing. I know these models can suffer from a sticky EGR value so I asked to have it cleaned and they said this wouldn't be worth it and it would be best to replace the unit. They also said that 'we can't confirm this will fix the problem so there might be more work needed after this' - not inspiring confidence at this point!

I should say that the light is intermittent - some days it's there others it's not. when it is there it's a solid light and accompanied by three beeps to let me know there's a problem.

I also have the following to note on the car (which may have nothing to do with this issue but who knows?) ... When I reverse the car I get a combination of six beeps (standard I believe when selecting reverse) but sometime this gives me three short beeps and then starts to sound like reversing sensors until I get the flat line noise - considering I don't have parking sensors this really confuses me!!!

There is also a metallic rattling when the engine warms up which I think is coming from the exhaust (loose fitting perhaps?) from low revs up to about 1500rpm in the lower gears and then comes back after about 3/3500 rpm.

I don't just want to throw £200 at the problem on the garages say so when it might not do any good at all. Can anyone help with ideas or suggestions as to how to fault find the real issue and not just replace parts?

I've had the car about two months and it's covered 55k. Has a warranty with Warranty Wise but they don't want to know.

Thanks in advance,

Talkingheads

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Sun 22 Apr 2012 11:17
Citroen C3 - EGR Valve and engine diagnositcs - Railroad.

This is a very common problem area and is not easilt cured. Many people think (incorrectly) that when the MIL lamp comes on we just plug in a diagnostic machine and it tells us what the problem is. It is NOT as simple as that.

The car's ECU receives input signals, and also controls outputs. There are two main reasons why a fault code may be generated which are

1. A circuit fault, eg a component being either open or short circuit, a wiring fault due to poor connection etc.

2. An effect from something mechanical causing a component to read outside the ECUs programmed parameters.

If in your case the EGR valve is clean, free and works then your problem lies elsewhere. Codes such as P0401 "EGR Insufficient Flow" doesn't necessarily mean the EGR valve itself is faulty. You need to check the entire EGR system to ensure it isn't blocked or that there aren't any air leaks. The ECU knows that the EGR valve has opened when commanded to by detecting the consequent reduction in mass air flow. If this reduction is not detected for whatever reason then the ECU will generate an EGR related fault code.

Your garage knows the job could be a headache and they'll be no obvious solution. That's why they're telling you to replace the EGR valve first, even though they know it probably won't cure the problem.

Modern cars are built with emission control first and foremost in mind. The EGR's purpose is to give clean emissions. When an engine is new this is never a problem, but as they age everything has some degree of wear. Eventually all this combined wear adds together to the point where the ECU is no longer satisfied that the correct emission standards can be achieved. This is when the MIL lamp comes on, and often there is no simple single fix.....

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Fri 5 Oct 2012 11:08
Citroen C3 - EGR Valve and engine diagnositcs - JoshVN

I've got the same rattling at low revs and random beeps. No warning lights though. Can I ask if you got the problem sorted out? If yes - how so? It's so annoying and getting funny looks from people.

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Fri 5 Oct 2012 11:09
Citroen C3 - EGR Valve and engine diagnositcs - JoshVN

(Because I don't get enough funny looks - driving a baby blue C3 as a 24 yr old male)

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