[Warning Light] risk of filter clogging

[liop_45@hotmail.com]

62 REG,berlingo , 1.6HDI.
Risk of filter clogging! .
That was the message, 
Next day I added almost 1 litre of pat fluid additive. 
3 weeks the yellow triangle had gone away.
the triangle came back & stayed on. 

when I would start the car, 3 messages would flash , engine fault, risk of filter clogging & add low. 
I had it reset and 2 days later the triangle came back & would flash on & off any time I hit 3000 revs.
Then I had a regen but 2 days later same again, triangle would come on & off .
I wanted to change the DPF filter but the filter was clean on the bottom & on the top was abit black, So I fitted the old filter back on as it looked good.
Now the triangle comes on for a day, on & off.
next few days everything looks fine as the triangle light does not come on


I need help as I dont know what the problem could be.

[Sol]

Probably the differential pressure sensor for the dpf is faulty or has a bad wiring connection. Cars have to measure the dpf pressure against something else to know if it's clogged, so I'd start there. Usually there is some kind of pre and post dpf sensors measuring pressure or flow. The 3000 rpm issue will be due to back pressure being measured. You don't have collapsed rear silencer internals do you? Or has someone stuffed something up the exhaust ? (Like the old potato up the tailpipe nonsense)

[liop_45@hotmail.com]

Probably the differential pressure sensor for the dpf is faulty or has a bad wiring connection. Cars have to measure the dpf pressure against something else to know if it's clogged, so I'd start there. Usually there is some kind of pre and post dpf sensors measuring pressure or flow. The 3000 rpm issue will be due to back pressure being measured. You don't have collapsed rear silencer internals do you? Or has someone stuffed something up the exhaust ? (Like the old potato up the tailpipe nonsense)

I have located where the dpf sensor is, Is there a equipment or tool to see if the sensor is faulty ?.

the exhaust on my berlingo comes out at the side of the car , under the rear passanger sliding door, due to the vehicle been a wheelchair access car. 
the exhaust under the car looks like an L shape.

[Sol]

There's a diagnostic tool called Diagbox that works with a hardware interface known as Lexia. These are specific to Citroen /PSA group and most on eBay or Amazon are Chinese clones though they work well, especially the "full. chip"  ones. Has to be installed on a win 7 or xp laptop / notebook. V7.83 works well and the kit of cables and software is usually under £40. The installation can require a few careful steps and a wee bit of patience.

Once you get it going, it's a great bit of kit - allowing diagnostics and customisation of car features. That would test the dpf sensor and measure what your back pressure is, as well as many other useful things you can do with it.

Here's a link to one that Cancunia found on eBay: eBay Lexia Diagbox kit

That one is under £35, good price. Don't be tempted to get a generic obd scanner, it won't work much if at all on a Citroen. Use that linked kit and a cheap older notebook off eBay if you don't have one already.