Adblue system fault, P20EE, P204F, P2195

[Natman151]

Hi,

Please can I have some help with this problem. I've had the emissions malfunction light come up on the dash and after running a VCDS scan it's showing these 3 fault codes:

15733 - SCR NOx Catalyst Bank 1
P20EE 00 [237] - Efficiency too Low
20553 - Reductant System Performance Bank 1
P204F 00 [101] - Malfunction
19249 - Oxygen (Lambda) Sensor B1 S1
P2195 00 [096] - Signal too Low (Lean)

I doubt it's coincidence but the adblue top up has also come on in the last couple days saying I have 600miles until it prevents starting.

Reducing agent injector: resistance 12741mOhm
Reduction agent dosing ReAg Rate/Demand:0.0/0.02 L/h / Reag Tnk Lvl:95.3 %
Reducing agent fill level 202.76%
Reducing agent fill level sensor: act. value 262 mm
Average reducing agent since lest filling 0l/1000 km
NOx-sensor NOx11:65535 ppm / NOx21:---
Measured NOx conversion 0
Calculated efficiency of NOx conversion 0.024
Efficiency threshold of NOx conversion 0
Calculated NOx concentration behind turbocharger 31ppm

I mapped all the values for the engine (attached) and these are the values i felt were potentially relevant, the main ones which look odd are the tank levels. Under dosing it's showing as 95.3%, another value shows 202% (how can it be more than 100%) and the actual raw value shows 262mm. Is there any test I can do to confirm the level sensor is working or re-calibration procedure? I don't want to just fill the tank hope. I've seen some forum posts which say the adblue system can get freaked if it doesn't see the level changing over time.

Another one that looked odd was the NOx11 value, 65535ppm seems like it's maxed out in fault. I'm going to log it on the way to work in the morning and see if the values change on a longer run. All this data was taken idle on the driveway.

Any help is appreciated, I'm not very familiar with the adblue systems. I've tried to attach as much information as I can and the full code scan below!


Chassis Type: 2K-VN35 (7N0)
Scan: 01 03 08 09 10 13 15 16 17 19 25 42 44 46 52 5F 61

VIN: Mileage: 133250km-82797miles

01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: Malfunction 0010
10-Park/Steer Assist -- Status: OK 0000
13-Auto Dist. Reg -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
5F-Information Electr. -- Status: OK 0000
61-Battery Regul. -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (J623-DFSD) Labels:. 04L-907-309-V1.clb
Part No SW: 04L 906 016 GT HW: 04L 907 309 K
Component: R4 2,0L EDC H20 1774
Revision: 8AH20--- CVN: 366C86B592F1EF3C
Coding: 01110012040509090000
Shop #: WSC 30017 005 1048576
ASAM Dataset: EV_ECM20TDI01104L906016GT 001003
ROD: EV_ECM20TDI01104L906016GR_001.rod
VCID: 015F8894718F02B3E4C-8054
VINID: 9E606AAAA09BA97A010C100900A2003486

3 Faults Found:
15733 - SCR NOx Catalyst Bank 1
P20EE 00 [237] - Efficiency too Low
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 3
Mileage: 132765 km
Date: 2022.12.04
Time: 20:23:14

Engine RPM: 2156.50 /min
Normed load value: 0.0 %
Vehicle speed: 110 km/h
Coolant temperature: 90 °C
Intake air temperature: 82 °C
Ambient air pressure: 1010 mbar
Voltage terminal 30: 14.840 V
Unlearning counter according OBD: 40
Long-term adaptation of reduction agent dosage: 1.00
Measured NOx conversion range 1: -1.000
Calculated efficiency of NOx conversion: 0.964
Efficiency threshold of NOx conversion range 1: 0.080
Current temperature with NOx Reduction CAT: 261.6 °C
NOx sensor after SCR cat conv: offset correction factor: 29 ppm

20553 - Reductant System Performance Bank 1
P204F 00 [101] - Malfunction
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 133172 km
Date: 2022.12.12
Time: 07:36:29

Engine RPM: 1835.50 /min
Normed load value: 76.1 %
Vehicle speed: 93 km/h
Coolant temperature: 90 °C
Intake air temperature: 102 °C
Ambient air pressure: 990 mbar
Voltage terminal 30: 14.840 V
Unlearning counter according OBD: 40
Reducing agent quality sensor: urea concentration: 0.0 %
Measured NOx conversion: -0.355
Calculated efficiency of NOx conversion: 0.935
Efficiency threshold of NOx conversion: 0.068
Current temperature with NOx Reduction CAT: 297.5 °C
NOx sensor after SCR cat conv: offset correction factor: 29 ppm
Reducing agent quality sensor: raw temperature value: -273.1 °C

19249 - Oxygen (Lambda) Sensor B1 S1
P2195 00 [096] - Signal too Low (Lean)
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 132831 km
Date: 2022.12.05
Time: 08:19:19

Engine RPM: 1538.50 /min
Normed load value: 0.0 %
Vehicle speed: 78 km/h
Coolant temperature: 88 °C
Intake air temperature: 49 °C
Ambient air pressure: 1000 mbar
Voltage terminal 30: 14.780 V
Unlearning counter according OBD: 39
Mass airflow sensor 1 bank 1 airflow: raw value: 550.6 mg/stroke
Mean injection quantity: 0.00 mg/stroke
Particl.filt.: different.press.sensor 1 bank 1: adaptat. value: 59 hPa
Oxygen sensor bank 1 before oxi cat: electric. corrected Pump current: 0.0032260 A
Oxygen sensor bank 1 before oxi cat: heater activation: 45.032 %
O2 sensor bank 1 upstrm oxi cat: status of signal quality: 1
Oxyg.sensor bank 1 before oxi cat: curr.pump curr.adaptation: 0.8174

Readiness: 1 1 0 0 0

-------------------------------------------------------------------------------

[spudboy6]

The first two are just saying the adblue system isn’t working ,

The only real fault code you have for a component is your lambda sensor , your need to sort this out first then go from there ,

Once that’s resolved if your still having issues your need to remove the vaporiser injector in the exhaust and check if it’s been leaking and crystallised over ,

Also once you’ve replaced items your have to do a long run at operating temp for the adblue system to reset ,

Be mindful of your 600 miles to non start . This is because your adblue system is not working and it’s there way of forcing you to get it fixed before you kill a butterfly or poison a flower

[Natman151]

Thanks for the reply, that makes perfect sense. I'll get the lambda sensor looked at and hopefully that fixes the issue, is there only one sensor? As far as I know it's before the DPF/Cat.

Do you think the tank levels are weird or is that normal?

[LouisAMS]

Did you clear faults then autoscan? As the lambda is intermittent.

What iso code does your adblue have?

[spudboy6]

Thanks for the reply, that makes perfect sense. I'll get the lambda sensor looked at and hopefully that fixes the issue, is there only one sensor? As far as I know it's before the DPF/Cat.

Do you think the tank levels are weird or is that normal?

It’s bank 1 sensor 1 so it’s the very first sensor in the system after before the cat , but if you ask the dealer for bank 1 sensor 1 they will give you the correct one

I’ve learnt not to always trust every bit of data over the years , I’d fill the tank and then check it , but all them sensors are internal into the tank and can’t be changed separately . Also I would expect a fault for level or pressures etc if they wasn't in range
Personally I would sort the O2 sensor. Clear faults , take it for drive cycle down the motorway and then report back

I fitted a new tank to a A8 the other week and after fitting and clearing faults the light went out before the end of the road . Other times I’ve had to do 20miles on the motorway ,
If there’s no hard faults for adblue it will reset once it’s at operating temp and done a drive cycle …. In theory

[Natman151]

To be honest I was skeptical about the tank level being off for the same reasons, it just looked odd. I'll fill it today and see what it does. My fuel consumption is terrible at the moment which also backs up the bad o2 sensor theory. Hopefully that sorts it! I'll let you guys know how I get on.

[Waquas]

Hi can anyone help im getting a fault code P203A00 and also amber adblue warning with a spanner on display.

[Natman151]

Hi guys, bit of an update, after a bit of debate with the dealer I agreed to get it assessed and repaired by a main dealer garage. They found that my O2 sensor was healthy and the fault was caused by a faulty NOX sensor.