C5 X7 2.0HDI P1490 (FAP overloaded)

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XUD9
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C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by XUD9 »

Hello guys - greetings from Bulgaria! :) I've been reading the forum for a long, long time. Saved me a lot of times with solutions. But now I've reached a dead end and need your help... :)

Recently, one of my dreams came true - I bought Citroen C5 X7 2012 (facelift) 2.0HDI RHF 138hp with FAP (millage: ~150 000km) . And the show began...

I'm getting the well known fault code P1490 (Risk of clogging FAP/PEF overloaded) since I've got the car. The regeneration is starting every 150-200km (the mirrors are getting hot) . I'm driving 90% highway . No problem I thought - just need to remove the filter for cleaning, as I was doing dozens of times to my friend's HDIs. But I was surprised when found out, that the FAP is solid and it can't be opened. However - removed it and wash it with high pressure water jet and degreaser. It was totally blocked with Eolys red ash. There was almost no sooth inside (no black water) . After the procedure - the filter was dried with compressed air. No oil deposits found before washing it.

That was easy I thought. I made a reset - replacement of the FAP, via Lexia, just in case. Most probably the previous owner also did it, because it was showing "cumulative weight of Eolys in the FAP - 2g - absolutely far away from the reality. After 180km of driving (one run, out of the city, without stooping the engine) - I've got the same message again...
After the procedure, the differential pressure drooped significantly - max about 40mbar / 3000rpm (stationary) . Before: 300-350-400mbar. The car ran much, much better after the procedure. Even the fuel consumption dropped with about 0.5l/100km. Ok, maybe it can be a result of different road conditions, but for sure there was an improvement it the acceleration.

The sensor is faulty I thought. Next day I've got OEM differential pressure sensor from Citroen (also replaced it by Lexia) . No change - still having the code in every ~200km.
I've got also P1351 (glow plugs not working) since got the car . But according to Service DocBackup - it's not linked with the problem. I've read about BMWs, that the regeneration is not starting if there are faulty glow plugs. Their row is to ignite the post-injected fuel and increase the temperature of the FAP. Is it the same here? Of course I'm planing to replace them, but I don't have free time right now...

I've checked DocBackup for clues. The first solution for P1490 is "Check air cooler bypass intake" . I see the flap after the cooler radiator (next to the MAP and MAF) , but can't figure out how the engine is getting fresh "heated" air during regeneration. I see only the EGR pipe, coming to the air intake manifold and no other sources... It's not enough by my opinion. There should be another pipe for air...

Eolys tank - still not checked. According to Lexia - it's almost full, but who knows... I don't think it's linked with the problem, because I've got the fault code immediately after washing the FAP.

And here we are today - totally confused, with no ideas left :) Maybe the glow plugs, or the FAP is totally stuck and needs replacement (but the car runs fine) , or there is something wrong with engine's ECU. Who knows...

Thank you in advance for the ideas! Cheers!
Ivo

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GiveMeABreak
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by GiveMeABreak »

So as you know the DPF gets filled with:

Carbon particles
Cerine
Deposits from the engine oil and engine wear

Only the soot really gets burnt off during regeneration and it is the Cerine that cannot be burned off. So it is the solid Cerine particles that ultimately block the filter. I doubt any amount of washing or pressure washing will get rid of it. You may be getting rid of some of the other deposits when cleaning it but I doubt you can get rid of the microscopic Cerine particles. So although your car may be performing a bit better, it may still being blocked within the octagonal structure of the filter.

Although you are doing motorway miles / speeds now, the previous owner may not. If the journeys of the previous owner (s) were shorter stop and start trips, then this would likely mean more frequent clogging and more assisted regenerations taking place. If those regenerations get interrupted frequently, then clogging will happen more frequently and possibly to a higher percentage before a regeneration can take place.

It won't be the additive fluid as you'll get a separate warning about the low fluid level in plenty of time.

If there was a fault with the differential pressure sensor, that should throw a fault code up. So you may have to bite the bullet and just get a replacement DPF - they don't last forever.

The glow plugs do play a role in postheating - the BSI commands the engine ECU to operate the glow plugs if it is necessary to 'load' the engine, but they are only active for about a second. That fault is a common error that just about everyone has with these engines - most without incident.

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Paul-R
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by Paul-R »

I have seen YouTube videos where the combined FAP/cat is cut open and then the FAP cartridge is taken out and cleaned. The cartridge is then put back in and the case welded back up.

Obviously you have to have welding capability but you might then have a problem with your next MOT when you might have to convince the inspector that the FAP hasn't been cut open to gut it!

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xf1ref
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by xf1ref »

I've seen in my country at garages two different methods to clean the FAP.
1. The first one is with some chemicals and high pressure water. There are dozens of movies with this procedure on YouTube.
2. The second one is with very hot air (no water or chemicals) and, as Paul said, some garages even cut the FAP case to clean the remaining Cerine with some thin wires. Then they weld back with stainless steel.

Ivo, I think also in Bulgaria you can found the same methods to clean the FAP, since we are neighbors.
Also at my car the FAP is almost to the end of his life and, to be honestly, I don't know which method is the best to try cleaning.

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XUD9
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by XUD9 »

Thank you all for the fast responses! :wink:

I have welding equipment and use it regularly. Was thinking about such solution, but I'm afraid that the ceramic dampers of the FAP are going to crack during the cutting... Looks too fragile.

The welding seam is not a problem. After all the things are different here, you all know... Most of the cars are with totally removed DPFs, because it's easier and cheaper for the owners. Unfortunately this is the reality. Totally disagree with such actions.

There are dozens of methods for cleaning. The latest modern one is "carbon cleaning" , with special magical chemicals (without removal) . But it will work for engines different from ours - with technology that don't use Eolys. As I know - there is no way to burn/clean the cerine ash (without removal) ...

There is also "oven" cleaning - the DPF is heated and the carbon particles are burned. Like real regeneration - the difference is that the temperature is not coming from exhaust gases. Unfortunately will not work for our cars, or it will burn only the sooth.

And the most popular one is cleaning with water and some detergent. It's the first time when I'm doing it and don't work. Of course it's on my car :rofl2:

My biggest fears are the things that Marc said. I will make last attempt for washing, but this time with special chemicals for FAP cleaning. If there is no change - I'll replace the filter with new one.

Hell Razor5543
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by Hell Razor5543 »

I cannot promise this will work, as I have not done it myself. However, I seen it posted up on this forum several times. I would suggest you do a thorough search on this forum for more information.

Remove the DPF and then leave it soaking in oven cleaner for a while (not sure how long). Then rinse it out until the water runs clear.

Oh, I like your Avatar image, by the way.

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GiveMeABreak
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Re: C5 X7 2.0HDI P1490 (FAP overloaded)

Unread post by GiveMeABreak »

You are correct in that the internals are very sensitive. They have a special cement and this can easily disintegrate iwirh knocks or force.

Remember the ash and soot burns up normally in the process unless it has been unable to regenerate. A filter can become permanently blocked and unable to regenerate at anywhere over 70% clogged.

This is where a deep clean is needed but important to ensure that there is nothing stopping the regeneration process.

The Cerine elements are non organic and cannot be burned off as I mentioned and I doubt they can be properly washed out to be honest so it’s really a service item and has done its job.