Adblue tank repair details

[Paul-R]

Brand Name FLUHANDY
Part no. HM8500J or HM8500F

Strange that there should be two part numbers. What is the actual difference? Is it a case that dimensionally they are the same but just the triggering pressure alters perhaps?

[Stuart W]

Diagnosing a faulty pressure sensor is best done without a diagnostic since the diagnostic is attempting to read its data from the faulty component .
There are 2 common sense methods which you can use.
1) If you have the Adblue system error lights or the diagnostic P20E8 code yet have heard the sound of the adblue pump running louder and longer than usual, it is a pretty safe bet that it is due to the failed sensor not reading any pressure so the system tells the pump to work harder and longer despite being aleady over the required pressure.Almost any other fault in the adblue control system would not result in the pump doing this.It is far more likely that the pump would not run at all
2) To confirm the pressure from the pump is high, it is simple to unplug the adblue tanks output pipe and plug in a cheap pressure gauge which will show the adblue pressure once the engine reaches operating temperatures and the adblue pump runs.
Anything over 6 bar points to the sensor being faulty.
Most other faults,be they in wiring plumbing or electrical areas will all result in low or no pressure.
So if you hear your adblue pump running noisily and for long periods it is almost guaranteed to be the faulty pressure sensor.

[PlayBloater]

Hi I have 2015 C4 GP with the P20E8 fault.
Had someone plug in and reset the system and tell the ECU that a new part was fitted and the fault came back with 15 minutes.

So we did a bit of diagnosing (father in law and I) and neither of us have heard the pump running at any point.

Can I just sense check?

When should the pump kick in?
On start up or whilst up to temp?
If the fault code comes on does that essentially shut off the AdBlue system?

Lastly if the pumps not running is the only option a replacement tank?

Thanks in advance.

(I miss cars without brains, oh a simpler time)

[meyouall]

Hi, I was wondering if this sensor is the same as the one used in Peugeot Expert 2019 vans?

I get P20EE fault code. My launch scan diagnostic tool shows the ‘Pressure of the urea fluid’ as 0.5 bars, not the normal lowest value of 4 bars. I read on a thread that 0.5 bar indicate that “the pressure sensor is disconnected”. By disconnected he probably mean malfunction.

So for the second solution just do the usual...........which would be;
1-Drain tank
2-Drop tank
3-Disconnect Adblue supply pipe
4-Disconnect wiring harness
then
5-Remove pump module from tank unit

At this point there are 2x cable connections to undo and 2x screws. NOTE (these are pentalobe 5 point screws and I didn't have one so I carefully used a suitable sized small flathead screwdriver, easy as they are not very tight) and then you can swap out the pressure sensor for a replacement. Then reassemble and refit the tank to car, refill with adblue etc. It would be a good idea to use Diagbox to reinitialise the adblue system as it runs a test at the same time though in most cases this would not be required if all adblue related codes have been cleared from the system.

The photo shows the multicore white cable connector disconnected from the pcb and the sensor black 3 core connector, both disconnected, and with the 2x pentalobe screws as fitted.

[Trickiedickie]

Hi, I was wondering if this sensor is the same as the one used in Peugeot Expert 2019 vans?

I get P20EE fault code. My launch scan diagnostic tool shows the ‘Pressure of the urea fluid’ as 0.5 bars, not the normal lowest value of 4 bars. I read on a thread that 0.5 bar indicate that “the pressure sensor is disconnected”. By disconnected he probably mean malfunction.

No. I think your problem is elsewhere. First I would check the adblue injector. Also check the DPF.

[meyouall]

dpf values are fine and checked adblue injector already, it isn’t clogged.
[/quote]
No. I think your problem is elsewhere. First I would check the adblue injector. Also check the DPF.
[/quote]

[rrc102]

Just wanted to add my thanks to Stuart for working this out. I had a high pressure error rather than low (P3054), but successfully carried out the fix over the Christmas break.

[Trickiedickie]

Just wanted to add my thanks to Stuart for working this out. I had a high pressure error rather than low (P3054), but successfully carried out the fix over the Christmas break.

Code P20E9 is pressure too high on the adblue system. Pressure too low is code P20E8

[rrc102]

My diag tool was giving

P3054 - Pressue of the urea fluid. Urea fluid pressure too high
P20E9 - Pressue of the urea fluid. Drift upwards

Take your pick.

[Trickiedickie]

P3054 - Pressue of the urea fluid. Urea fluid pressure too high

Not seen that one before. Maybe it is not from Diagbox but another manufacturers diagnostic tool?
Well done for sorting a fix!

[JC Mar]

Some of you may have seen my posts on here when my 2015 Grand picasso suffered the all too common adblue pump failure with persistently screaming pump and Service light on, engine fault light and urea light on.
Diagbox says leak/ low urea pressure.
It is worth noting that diagbox says pressure is 4 bar even when its actually zero.It does not read below 4 bar.
However, when I removed the tank and ran the pump directly from 12 volts with a pressure guage attached to its output, the pressure shot up immediately way past the required 6Bar, reaching 8 or 9 bar in seconds.So the pump was not faulty.
The culprit was the pressure sensor that is built into the pump body.I metered the output from this sensor and it did not register the pressure changes at all.This explains why The pump was screaming, trying to reach a pressure that was not being seen by the sensor although in fact it was already too high.
The faulty sensor also mislead diagbox and me for a while, by saying the pressure was too low.The system will not inject the adblue if it thinks the pressure is too low.
This noisy overworking adblue pump seems to be a commonly reported problem so I suspect that the majority of adblue tank failures are due to this sensor.
THE FIX.
Since the original sensor is a purpose built part moulded in plastic and attached to the pump motor it cannot be replaced without PSA manufacturing a spare part.
The answer is to fit an external sensor in the urea output pipe that runs to the injector.
I bought some 6mm fuel line connectors, male and female ant with some 8mm hose and 8mm brass tee piece inserted this short extension pipe from the output of the blue tank.The Tee piece connects to an 8mm to femake G3/8 thread adaptor to accept a standard 3 wire pressure sensor (10 Bar)
The existing Citroen pressure sensor has a small 3 pin plug with red,black and yellow wires.Unplug this from the sensor and connect the new sensor to the same wires.In my case the new sensor had a green wire instead of yellow, but connect this green wire to the yellow of the Citroen lead. The Red wire is + volts supply and the black wire us - volts supply.The yellow or green is the sensor output which should move from 0 volts up to 5 volts as the pressure increases.
Since the sensor comes with about 30 cm of wire attached you will need to drill a small hole in the plastic lid which covers the pump and its electronics.
Feed the sensor wire through this and connect the red, black, green wires to the old sensor lead.Seal the cable hole to prevent dirt and moisture getting to the electrics.
While the tank is out, it is worth offering up the Tee piece extension hose to find a suitable location for the sensor to fit as space is limited between the adblue tank and the spare wheel.Adjust the hose length to allow the sensor to fit into one of the recesses in the tank moulding.
For belt and braces, I put two jubilee clips, close together, on each pipe joint. So 12 hose clips in all.
It may be necessary to bleed the adblue system with diagbox before clearing all error codes.In the course of doing this mod I have only had to bleed the system once.Previous times it was ok.
To see what is happening with your faulty tank it is worth checking the pressure by using a piece of this same 8mm pipe and clip on 6mm fuel line connector running to a 0 to 10 bar pressure gauge, also available from ebay or Amazon.Once the engine is warm the adblue pump should operate periodically to bring the stored pressure up to 6 Bar.
If your adblue pump is screaming and the fault codes are saying low pressure then it is worth doing this low cost fix.
All parts were bought from Amazon for a few pounds.See my attached photos.

_________________________________________________________________________________________

Hi Stuart
Congrats for the really good job done and modification applied for externalizing of the Pressure sensor.
I have fixed already quite a few Adblue Units of PSA Group, sparing the sensors out from other used units, replacing them as the inside space where the Press Sensor is located is really tight.
However your alternative is brilliant, I have just a couple of questions related to it, of you can reply, much appreaciated;
1.- Can you confirm it really works with a commercial standard Pressure Sensor, (type 0-10Bars for water and fluids, feed 5 V, three wires) ??
2.- Does the unit still maintain the average Pressure when the system is in service, around 4-6 bars ? it does not scale to upper pressions ? ( I imagine the software in the base bard regulates the pressure..., in other words, the Adblue board does not notice if the Sensor is 0-8 Bars or 0-10 Bars a standard model.)

Many thanks in advance for your appreciated advice.
Cheers.
JC

[SoyezFerme6789]

Hello! Many thanks to the OP. Is there a recommendation for which pressure gauge, currently available on Amazon, to purchase? I'm trying to sweet-talk my mechanic into trying this solution for a faulty UREA/Adblue tank/sensor situation. He is most concerned about getting that pressure sensing part, right, understandably. I'm not mechanically trained in anyway, but hoping to save myself 2k+AU$ on a new tank, with a little help. Cheers!

[Stuart W]

Hi JC, sorry for the delay in replying.Yes the standardly available 3 wire liquid pressure sensors are perfectly ok.They have a linear response so give out a proportional voltage which rises related to the pressure.This varies from 0 to 5 volts .Only the adblue board relates this to a pressure and this seems to be set to an "ok" range at around 60 percent of the maximum.Hence the board interprets the voltage from the sensor as ok.I aimed for 6 bar actual pressure, so fitted a 10 bar sensor.I am sure that if a lower pressure sensor was fitted, the system would still receive the ok signal but at a real pressure that was lower at around 60 percent of the sensor rating. However since the actual emission reduction would be lower, the exhaust monitoring sensors would be asking for more frequent adblue injections.
As regards constant pressure the adblue has a spring loaded storage system which maintains the required pressure without the pump running constantly.The pump only runs when this stored pressure becomes too low.

[JC Mar]

Hi Stuart.
No reason to say sorry, just the opposite to thank you for your contribution.

Thats indeed what I thought and it is consistent precisely with your comment, I have replaced my press sensor with that one of 10bars and it works just fine. I encourage those facing the same issue to put it into practice, as the original sensor is nonsenselessly expensive and rather hard to get from the web , (moq quantities for order, different specs, etc) .
Thanks again, I have performed a full overhault to my Urea tank, and also I have externalized more elements, just as the pump and the pressure accumulator, they can also be reallocated outside for safe ooeration and easier intervention in case of breakdown.
Good job !
Best rgds.
JC

[DaleG]

Hello all!

Apologies for bumping, but I just wanted to relay my experience in fixing my AdBlue tank by purchasing the sensor posted earlier by Trickiedickie. https://www.alibaba.com/product-detail/ ... 69608.html

I had the low pressure fault, along with hearing the pump screaming from the rear of the car as soon as my cat got to temp, so based on Stuart's initial post pointing to a likely failed sensor I ordered a couple from that link. One of the reviews stated theirs arrived mechanically damaged, so ordered a spare for some insurance; it cost me I think ~£70 for the two delivered to the UK. The factory appear to have two specifications for that same SKU and I was asked which I wanted in a DM on Alibaba. A 4-7 bar sensor and a 0-13 bar. Based on the diagram posted again by Trickiedickie, and seeing 4bar as the base value in scanner live data, I opted for the 4-7 bar sensor. Took maybe 1 month ish to get here, and it was a dead simple part swap. The screws around the top of the tank were rusty as hell, but I cleaned them out best I could with a sharp pick and just went steady.

Car is working good as new. Soon as the cat hits 175, it pressurizes up to ~6bar peak, settling at around 5.8 bar. Then slowly trickles down while the cat remains at temp to ~5 bar at which point it quickly re-pressurises back to 5.8.

Thanks for all the info on this thread. Saved a good few quid. I also now have a spare AdBlue sensor sat on my parts shelf, so if anyone is desperate for one I can chuck it up on eBay. Thanks again chaps! I encourage anyone who may be lurking this thread like I was to give it a go.