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Adblue level sensor fail 2015 C4 Grand Picasso

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Fri Nov 18 2022, 07:33pm
Member No: #60261
Joined: Nov 18 2022
Location: Brisbane Australia
My very first post. Hope I'm in the right area. My car has done 81K KMs. Got the Urea refill message. I filled the tank using 10L container. Message did not reset. 300 KMs later warning message still on so started troubleshooting. Used Autel AL1619EU diagnostic tool which can read the SCR system. All components of the Adblue SCR system are working. No DTC error codes. But it showed there are 5 additive low level readings in the system. In my case low_level, low_level1 and low_level2 are showing YES meaning low level, and low_level3 and low_level4 are showing NO which means fluid is detected. My tank is full. I don't know the positions of each low level sensor so not sure if it thinks the top half of the tank is full and bottom half is empty.😁

I don't want to replace a whole tank for over $4K just for a level sensor. I'm thinking if I knew what sort of signal the sensor sends to the ECU, I could maybe put a fixed signal in the line to trick the ECU into thinking the tank is always full and then I just keep the tank topped up every few thousand KMs.

Or has anyone had experience with changing the level sensor set points in the ECU? So far, my only option is a new tank or an Adblue delete. I don't want to do either. Fixing a level sensor should normally be easy, but not in a hermetically sealed adblue tank. Wires can be easily accessed by removing the control module on the top of the tank so it would be easy to wire in a fixed resistor or capacitor or whatever, if I only knew what type of level sending signal is used. Information on this has been impossible to find so far. PSA is keeping this knowledge out of the public domain I'm thinking.

Hope someone can help. Great forum and web site by the way.
Sat Nov 19 2022, 12:21am
Member No: #60261
Joined: Nov 18 2022
Location: Brisbane Australia
Well .... this is one of those "I don't believe it" moments. After posting my first topic, I did even more googling (It's been over 2 weeks on this now) and found a suggestion that the tank might be overfull and the level sensors don't cope. When the countdown was down to 1800 km from 2400 km, I added 10 litres. The Urea light didn't clear and so I added another 2.5 litres. The tank overflowed from under the car. When it settled, I could see the fluid level in the tank filling pipe (under the third-row seat). The UREA warning light stayed on. So, having done everything else, I assumed the tank must indeed be too full, and I decided to empty the tank and start again. I estimate I drained about 19 litres. The tank is supposed to hold 17 litres. I put 14 litres back in as I didn't know how much was left in the tank. Then I followed other suggestions. I let the car sit for over 10 minutes with doors shut and the key fob out of range. I pressed the Start button without foot on brake to just turn on the ignition. The UREA warning light went out!!! I had a look in the tank and I couldn't easily see the level of fluid in there. Having done nothing else, I can only assume that I did indeed overfill the tank, the sensor stopped working, and draining the tank and refilling with the correct quantity has worked.

I checked my diagnostics again. The only change was that the Low_Level reading changed from YES to NO. Low_Level1 and Low_Level2 were still YES, and Low_Level3 and Low_Level4 were still NO. I don't know if this will mean an early fill warning perhaps in less than the usual 10,000 kms.

So, what does that mean going forward? There is no way to know how much fluid is in the tank. So, should you top up with 5 litres immediately the first urea fill warning shows? Or wait until the last 300km warning (with annoying warnings at each start for 2,000 kms) and fill with 10 litres? A tricky decision to make.

Anyway, I hope this experience saves someone else from getting a new tank unnecessarily. And just a recap - the only warning was the UREA light. There was no SERVICE or engine symbol warnings. If you also get either of the latter two warnings as well as the UREA light, then you are more likely to have a component failure that will need a new tank.
2 User said Thank You to Robbie2015 for this Post :
 skorpion (19 Nov 2022 : 02:50) , DeuxChevaux (19 Nov 2022 : 03:25)
Tue Nov 22 2022, 08:42am
Member No: #46470
Joined: Oct 11 2016
Location: Cambridge
Anyway, I hope this experience saves someone else from getting a new tank unnecessarily.

Thank you! This will sit deep in my memory in case similar happens to me. Back in the day, AdBlue top up was a standard part of the annual service - no longer - and I often wondered how they knew what was in there. I asked the service manager, they didn't! Guesswork. Maybe it depends on the length of the technicians finger when they stick it in the tank.

(This is a useful forum, but not many people follow up post when they have found a solution. You join an elite minority )
Fri Feb 17 2023, 06:42am
Member No: #60261
Joined: Nov 18 2022
Location: Brisbane Australia
I have a new update for this thread. Early Feb 2023, approx 2 months after I managed to reset the Urea low level as described in November, the Urea warning light came on again. Drained the tank and collected 13 litres meaning I'd used about a litre in 2 months which is reasonable. Filled tank with 15 litres. This time the Urea warning didn't reset. I waited until counter got to 1800km to go. Still on so gave up and took it to my Citroen dealer for diagnostic. They said I had crystals on the level sensor. How diagnostics could tell that I'll never know. I suggested they flush the tank then. No can do. Sealed tank. Need a new one at big cost. Nothing to lose now so decided I'd take the tank off and check wiring, connectors and whatever else I could access. Before that I googled a bit more and found a couple of additive products that claim to dissolve adblue crystals in the tank including the level sensor. One is Forte Exhaust Crystal Cleaner and another is Wynn's Crystal Clean and Protect. Not available in Australia. Wynn's UK says it's only been around a few months. I'm prepared to have a go and ordered a bottle. I'll let you know how it goes. Probably take a month.
Fri Feb 17 2023, 01:17pm
Member No: #55124
Joined: Nov 28 2019
Location: West Yorkshire
Forte Exhaust Crystal Cleaner

Just added this to my AdBlue tank as a precaution, as I've seen others mention crystal build-up.
Sun Feb 19 2023, 08:58pm
Member No: #60261
Joined: Nov 18 2022
Location: Brisbane Australia
Citroen Australia just playing with me. They told me to take the car to my local dealer for diagnostics to see if Citroen would offer a contribution to the repair. Just got a call from the dealer. The results were sent to Citroen Head Office and they said NO! Then I had to weadle out of them what they thought the problem was. Crystallization of the Adblue affecting the level sensor and Adblue injector. I asked how they worked that out from diagnostics. They said it's just what happens to these tanks. "Had three last week". So, what level was diagnostics saying was in my near full tank? Can't tell when level sensor is gummed up with crystals. I insisted they show me the results of the diagnostics. They refused because it's confidential??!! Seriously?? It's my car. I'm entitled to know what you found. NO! Confidential! I then said - Oh, I see, Citroen is hiding something. The conversation just got very much worse after that. What a total joke this all is. And if indeed crystals have formed on the level sensor, then why can't these tanks be cleaned with a solvent or something so the tank will last another 80K? In frustration, I've sent a complaint to emission standards at the EU Commission about allowing companies to build adblue tanks that can't be serviced or cleaned when it is known how much Adblue can crystalize. Who knows where that will go. Just a further note that these crystals haven't formed due to low temperature or a faulty heater. I live in Queensland in Australia which is tropical. In the meantime, I will wait for my adblue crystal cleaner and let you know how it goes. Sorry about this, but I just needed to vent somewhere. Thanks for reading.
Sat Apr 01 2023, 03:24am
Member No: #60261
Joined: Nov 18 2022
Location: Brisbane Australia
Update. I received my order of Wynn's Crystal Clean and dosed the Adblue tank. After 300kms unfortunately it has made no difference and my level sensor is still causing the Urea light to remain on. Maybe it is broken and not just gummed up. Next step will be to drain the Adblue tank and fill with hot water couple of times to give the tank a clean. If that doesn't work, then the dilemma of renew or delete will be the next step. I have made a claim on Citroen Australia saying the tank is not fit for purpose. They got the problem diagnosed; wouldn't tell me the results; told me to buy a new tank for $5000 and have refused to answer any more of my emails or phone calls. I made a formal complaint to ACCC. Thanks but go to fair trading. Just sent the complaint to fair trading. Not holding my breath.I will never again but a car that needs Adblue. All my research suggests it was really meant for trucks. I recently bought a new Hyundai Tucson diesel. No Adblue and no start/stop. It drives really well.
Sun Apr 02 2023, 12:51am
Member No: #52161
Joined: Sep 21 2018
Location: Republic of Serbia
I would personally disable Adblue with software. Best long term solution. Just for a reference, in Europe, new Adblue is about 1200e.

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