DS3 BlueHDi - Do these live data values look correct?

[MJJ_ZX6RR]

Hi all,

I am trying to diagnose an issue on my daughter's newly acquired 2016 DS3 1.6 HDi 120, a Euro 6.1 SCR/AdBlue equipped car. The car is displaying the fairly common, but not particularly helpful 'Emissions fault - starting will be prevented in 600 miles' message that is naturally counting down. The car is high mileage (153k) but well looked after.

Initially assumed to be low AdBlue, and the car did take 10.5l to fill the under boot floor tank, but message remains. I have followed the handbook advice on topping up the AdBlue tank - we have let the car sleep overnight, and held ignition position 2 for 10 seconds prior to starting.

There are three fault codes logged that come back after clearing and a short drive:
1) Parking systems module - P0BC3 Short Circuit to Positive - Interior Right Front Sensor Fault - no signal
2) Engine Control Module - Temporary fault - Fuel High Pressure Circuit , Fuel Pressure lower than the Reference Value
3) BSI Module - Fault inside the Built-in Systems Interface ECU: Output not working.

Looking at Live data on my diagnostics kit, I see the following (screen shots below). Any of this look out of place to anyone? I am particularly confused by:
- the NOx sensor values that don't change at all, with temperature, time nor revs.
- 'Authorisation of injection of the urea fluid based on pressure' being NO.
- Operating Status of the deNOx system: urea pump stopped.

If anyone has any tips or suggestions, I am all ears.

thanks,

Martin.

[GiveMeABreak]

The Urea Reservoir Heating power 0% and NOx sensor heating control are normal readings would be normal if the temperature outside is not too cold as the heating of the Urea Pipes is only activated when there is a risk of it crystallizing.

We've seen a few of these fail recently, but I can't see any fault relating specifically to the SCR system show in your posts, though that may be related to the diagnostic equipment. Whether Citroen / DS can reset or check the system to confirm whether the pump is faulty or not I can't say.

[MJJ_ZX6RR]

Thanks for the reply Marc, and thanks also for the part number details on the other thread also - you are a star.

I have just come back from my daughter taking me for a drive whilst I watch the live data. The testing earlier (screen shots in my first post) was idling on the drive from cold. What I can see from the live data during an up to temperature drive is that:
- Urea is successfully being injected, and the actual injected quantity mirrors the commanded quantity data PID pretty closely. Good news.
- I saw the AdBlue pressure value climb to 5.7bar and stay there when running - I saw 4 bar when testing earlier idling on the drive, but I am not sure what normal is.
- With the ambient temp being only 12 degrees above the freezing point of AdBlue, I can see the car command the reservoir heating circuit into action intermittently. Seems normal.
- The 'upstream' NOx value never deviates from zero, which fits with your parts schematic you kindly supplied showing only one NOx sensor.
- The 'downstream' NOx value does give potentially plausible readings when on the move, and they rise and fall as expected with engine load. However, I am suspecting the NOx sensor to be faulty as it gives a value of c. 2,000ppm on a cruise and 7,000ppm when accelerating normally. A basic google suggests the value at a cruise on an EU6 car should be more like 0-100ppm.

I have watched a DiagnoseDan YouTube video recently where he demonstrated that a number of aftermarket scan tools read the NOx PID way higher than actual, so I am going to try and find a way to get the car on Diagbox and go from there.

I think I will need Diagbox to code a new NOx sensor anyway.

Martin.

[GiveMeABreak]

Hi Martin.

Yes the NOx sensor needs initialising when replaced.

[MJJ_ZX6RR]

Hi Martin.

Yes the NOx sensor needs initialising when replaced.

Thanks again Marc. Do you, or anyone else, have any experience of initialising a new NOx sensor DIY with Diagbox? I am wondering if this comes under Telecoding which I believe is only possible (outside the dealer network) on older versions of Diagbox (7.x I think). Perhaps these old versions won't successfully talk to my daughter's generation cars.

Sourcing the genuine part, and fitting together with my daughter is straightforward and good experience for her - though no doubt some Plusgas and swearing will be required on a 153,000 mile NOX sensor.

Initialising the sensor once fitted is the gap in my knowledge however.

Martin.

[GiveMeABreak]

I haven't done this, but as far as I'm aware, it's not configuring the unit specifically which falls under the telecoding, but it's more like informing the engine ECU it has been replaced to it can initialise the sensor. There's no mention of 'configuration' only 'initialisation', which will be a replacement procedure and not a telecoding / configuration issue as far as I can tell.

[MJJ_ZX6RR]

Thanks again Marc. Do you, or anyone else, have any experience of initialising a new NOx sensor DIY with Diagbox?

I haven't done this, but as far as I'm aware, it's not configuring the unit specifically which falls under the telecoding, but it's more like informing the engine ECU it has been replaced to it can initialise the sensor. There's no mention of 'configuration' only 'initialisation', which will be a replacement procedure and not a telecoding / configuration issue as far as I can tell.

Just thought I would post back here in case it helps others in the future. I purchased, installed and successfully used Diagbox v9.91 over the Xmas period to initialise the new NOx sensor that had been fitted to my daughter's DS3. This was a simple routine run under the 'Repair' section of the tool, and so far (tempting fate here!) the 'Starting prevented in 700 miles' countdown has gone, and not returned.

Also managed to replace the failed front parking sensor which has kicked both the parking assist and emergency city brake back into action. Not too difficult a job other than a fairly hidden bolt that fixes the bumper to the front wing on each side.

Martin.

[GiveMeABreak]

Great, thanks for the update.

[wheeler]

This was a simple routine run under the 'Repair' section of the tool, and so far (tempting fate here!) the 'Starting prevented in 700 miles' countdown has gone, and not returned.

How long has it been since you done this (days and miles)? Dont count your chickens too soon, If the NOx sensor was not the issue it can take a few days to re occur after reinitialising the system. Fingers crossed though.
How easy did the sensor come out? Most times i usually have to heat them, then re tap the threads in the exhaust too.

As for the urea pressure readings these look normal, the pump pressure will sit at 4.0 bar exactly until the exhaust temperature reaches 176°C then the pump will kick in & it should go up to around 5.5-6.0 bar.

[MJJ_ZX6RR]

How long has it been since you done this (days and miles)? Dont count your chickens too soon, If the NOx sensor was not the issue it can take a few days to re occur after reinitialising the system. Fingers crossed though.
How easy did the sensor come out? Most times i usually have to heat them, then re tap the threads in the exhaust too.

As for the urea pressure readings these look normal, the pump pressure will sit at 4.0 bar exactly until the exhaust temperature reaches 176°C then the pump will kick in & it should go up to around 5.5-6.0 bar.

Thanks for the pump data, very helpful. No chickens have been counted as yet, but it has been a week now since the new NOx sensor and Diagbox reset. The rest of the urea system readings seem normal on live data, and only the NOx stood out as erroneous to me - so remaining hopeful. I am aware how common pump/injector/tank failures are on these cars, with the compounding situation that the complete £1,200 tank is the only replacement option.

I got my local garage to replace the NOx sensor as crawling around under jack stands in December did not appeal - they tell me it came out surprisingly easily, particularly for a 153k mile car. Perhaps it is already been changed once before.

Martin.