3.0L_TDI CATA | CNRB - Testing SCR Injector and SCR Adaptation resetting

[DrPeter]

N474-Reducing Agent Injector testing and Adaptation of Reduction Agent resetting​

Hello,

The following Ross-Tech forum posts outline the VCDS procedures for:

Generation 1

Audi Q7 (4LB_NAR) - MY 2009-2012​

V6 3.0L TDI 225hp - CATA Generation 1 TDI (2/2009 - 5/2012) [non-UDS]​

​

Volkswagen Touareg (7L6/7P5_NAR) - MY 2009-2013​

V6 3.0L TDI 225hp - CATA Generation 1 TDI (2/2009 - 6/2012) [non-UDS]​

• N474-Reducing Agent Injector - Test the output flow/quantity of AdBlue
• N474-Resetting of the learned SCR values - - Resets the SCR adaptations to zero point [1.01]

CATA Generation 1 TDI Tech Tip hosted by the NHTSA:​

TT 26-11-03​

2009-2010 Touareg – AdBlue light on with Tank Full​

https://static.nhtsa.gov/odi/tsbs/2013/SB-10069127-2280.pdf

---

Generation 2

Audi Q7 (4LB_NAR) - MY 2013-2015​

V6 3.0L TDI 240hp - CNRB Generation 2 TDI (5/2012 - 8/2015) [UDS]​

​

Volkswagen Touareg (7P5/7P6_NAR) - MY 2012-2016 ​

V6 3.0L TDI 240hp - CNRB Generation 2 TDI (5/2012 - 8/2015) [UDS]​

• N474-Reducing Agent Injector - UDS Only - Test the output flow/quantity of AdBlue
• Resetting of the learned SCR values - UDS Only - Resets the SCR adaptations to zero point [1.01]

​

CNRB Generation 2 TDI Tech Tip hosted by the NHTSA:​

26-18-03 TT​

Selective Catalytic Reduction (Adblue™) Light Reset​

https://static.nhtsa.gov/odi/tsbs/2019/MC-10163434-0001.pdf

 

[DrPeter]

Testing N474-Reducing Agent Injector [non-UDS controllers]

Summery:
Sometimes it will be necessary to test the N474-Reducing Agent Injector. Below is the procedures for non-UDS controllers, please follow all additional instructions, warnings, etc found in the Official Factory Repair Manuals. During this test the output of AdBlue from the N474-Reducing Agent Injector will be tested and measured.

We strongly recommend to check the SCR (Selective Catalytic Reduction) adaptation values before clearing any codes or testing, this will let you know if the Engine controller is either 'adding' or 'taking away' the amount of AdBlue that is being injected into the system.


This test should be completed if you have:

• NOx efficiency fault codes
• SCR fluid consumption too low or high
• Other similar NOx or N474 concerns.

Testing N474-Reducing Agent Injector [non-UDS controllers]

Component to be tested: N474-Reducing Agent Injector
Component location: Exhaust, upstream of NOx catalyst
Required time for test: About 20-30 minutes
Special tools: VAS-6532 (or a clear plastic container)
Prerequisites: Key on, Engine off and the use of a proper Battery Maintainer is required, test will run 10 or more minutes.

Special Notes: Follow the workshop manual and all safety precautions when working with the vehicle and when handling Diesel exhaust fluid (AdBlue)!



Procedure:

Step: 1

Select [01-Engine]
Select Measuring Value Block group(MVB) [183], press [Go!
- Make note of field (1)


Evaluation of MVB-183, field (1) - Learned SCR adaptations values:
A value of:
[= 1.01] = Default value after a reset (center-line value)
[> 1.01] = System is having to 'add' AdBlue to maintain NOx catalyst efficiency
[< 1.01] = System is having to 'reduce' AdBlue due to an over-dosage detection


Step: 2

At this time, remove the N474-Reducing Agent Injector from the exhaust and place it into the collection container.
Important: Do Not Disconnect the supply line or electrical connection!

To start the test,
Select Engine-01
Select Adaptations
- Read channel [54] (Should display [00 04]
- [Test/Save] a new value of [00 02] (values may reset and revert back to 00 04)

Select Basic Settings
- Group [170] (Pump Leak Test)
- Press [Go!] and if needed [On/Off/Next] to start the test. You should here the pump/injector make noises.

Group [170] Notes:
Field (1) = Activation of Reducing Agent pump in percentage (Should increase with Basic Settings On)
Field (2) = Reversing valve Status (if applicable)
Field (3) = Activation of Metering Unit in percentage (Should increase with Basic Settings On)
Field (4) = Reducing Agent Metering System Pressure Sensor - G686 (should be 5-6Bar)

Completion:
- The test will continue to run for about 10 minutes, when complete, it will automatically stop. Exit out of the controller.
- You should expect to have about 25-30ml in the catch container.
- Less could indicate the N474-Reducing Agent Injector is clogged or restricted or low supply pressure
- More would most likely indicate a leaking N474-Reducing Agent Injector or high supply pressure


If the N474 is to specification, be sure to verify the quality of the AdBlue is correct. You can check the concentration with a DPF/AdBlue refractometer.

If any repairs are made, you must perform the Adaptation, see posts below.



drpeter

 

[DrPeter]

Adaptation of the reduction tank - non-UDS

This Adaptation will re-set the value in the Measuring Value Block group(MVB) [183] for CATA Generation 1 TDI engines

So if you have not already done so, check the current value of the MVB-183 and make a note of the current value, key one, engine off.

You should only reset this if:

• Any repairs were completed on the AdBlue system
• The Rear NOx sensor was replaced
• The DeNox Catalytic Converter was replaced

To perform the resets:
Select Engine-01
Select Adaptations
- Read channel [40]
- [Test/Save] a new value of [00 64]

Then re-check MVB-183, field (1) to be sure the value has changed to [1.01].

It is very important to test drive the vehicle after the repair and reset at least 40 to 50 miles at normal speed limits on the highway. This test drive will ensure that the AdBlue is actually being consumed by the system. Short traffic road tests will not ensure the AdBlue system can learn properly.

Last step, after the extended road test is to check for fault codes and verify Measuring Value Block group [183] is close to [1.01]. The typical range can be from [0.90 to 1.10].



drpeter

 

[DrPeter]

Testing N474-Reducing Agent Injector [UDS controllers]

Summery:
Below is the procedures for UDS controllers, as usual please follow all additional instructions, warnings, etc found in the Official Factory Repair Manuals. During this test the output of AdBlue from the N474-Reducing Agent Injector will be tested and measured.

We strongly recommend to check the SCR (Selective Catalytic Reduction) adaptations before clearing any codes or testing, this will let you know if the Engine controller is either 'adding' or 'taking away' from the mapped amount of AdBlue that is being injected into the system.


This test should be completed if you have:

• NOx efficiency fault code
• SCR fluid consumption too low or high
• Other similar NOx or N474 concerns.

Testing N474-Reducing Agent Injector [UDS controllers]


Component to be tested: N474-Reducing Agent Injector
Component location: Exhaust, upstream of NOx catalyst
Required time for test: About 20 minutes
Special tools: VAS-6532 (or a clear plastic container)
Prerequisites: Key on, Engine off and the use of a proper Battery Maintainer is required, test will run 10 or more minutes.

Special Notes: Follow the workshop manual and all safety precautions when working with the vehicle and when handling Diesel exhaust fluid (AdBlue)!



Procedure:

Select [01-Engine]
Select Advanced Measuring Values, [Long-term adaptation of reduction agent dosage]
- Make note of field (1)
Hint: Use the filter on the pop-up (look for the key word "term")

Evaluation of Long-term adaptation of reduction agent dosage:
A value of:
[= 1.00] = Default value after a reset (center-line value)
[> 1.00] = System is having to 'add' AdBlue to maintain NOx catalyst efficiency
[< 1.00] = System is having to 'reduce' AdBlue due to an over-dosage detection
[0.90 to 1.10] = Normal working range


At this time, remove the N474-Reducing Agent Injector from the exhaust and place it into the collection container.
Important: Do Not Disconnect the supply line or electrical connection! refer to the Official Factory Repair Manuals

To start the test,
Select Engine-01
Select Adaptation
Select [Adaptation for metering quantity measurement]
Press Read ([Stored] value is typically [04])
Enter in a New Value of [02], press [Save]
Note: This step enables the Basic Settings, a key cycle will reset this to a value of [04]


Select Basic Settings
Select [SCR metering quantity test], press [Go!]
Then press [On/Off/Next]



Completion:
- The test will continue to run for about 10 minutes, when complete, it will automatically stop. Exit out of the controller.
- You should expect to have about 25-30ml in the catch container.
- Less could indicate the N474-Reducing Agent Injector is clogged or restricted or low supply pressure
- More would most likely indicate a leaking N474-Reducing Agent Injector or high supply pressure


If the N474 is to specification, be sure to verify the quality of the AdBlue is correct. You can check the concentration with a DPF/AdBlue refractometer.

If any repairs are made, you must perform the Adaptation, see posts below.



drpeter

 

[DrPeter]

Adaptation of the reduction tank - UDS

This Adaptation will re-set the value in Advanced Measuring Value group [*IDE03386*] Long-term adaptation of reduction agent dosage

So if you have not already done so, check the current value of the [Long-term adaptation of reduction agent dosage] in the Advanced Measuring Values with the key on, engine off.

You should only reset this if:

• Any repairs were completed on the AdBlue system
• The Rear NOx sensor was replaced
• The DeNox Catalytic Converter was replaced

To perform the resets:
Select Engine-01
Select Basic Settings
Select [*IDE03402*] Resetting learning values for reduction agent metering system from the pull-down menu.
Press Go!, you should get the message Finished correctly


Check the [Long-term adaptation of reduction agent dosage] in the Advanced Measuring Values to verify the value has changed to [1.00].

Like the Generation 1 TDI engines, it is very important to test drive the vehicle after the repair and reset procedures for at least 40 to 50 miles at normal speed limits on the highway. This test drive will ensure that the AdBlue is actually being consumed by the system. Short traffic road tests will not work, since typically no AdBlue will be used and thus system cannot learn correctly.

Last step, after the extended road test is to check for fault codes and verify the [Long-term adaptation of reduction agent dosage] in the Advanced Measuring Values has the typical range of [0.90 to 1.10], any more or less will eventually set a fault code.



drpeter