B7 RS4 Master & Slave ECU showing different emissions readiness

[alvinminassian]

I recently went through the emissions readiness cycle to get the vehicle ready to pass an emissions test, but after completing 100+ miles of driving and going through various test, I found that primary ECU (7E8) is showing all function having passed and ready for emissions test, but the secondary ECU (7EA) continues to show two function still remaining to be tested -- Catalyst monitoring and Secondary air system monitoring. I don't understand how the two ECU can show different results. Is it possible that the secondary ECU (slave) takes longer to update? Is there a way to get the secondary ECU to update manually to what the primary ECU is showing? Any advice how I can get the readiness set on the secondary ECU.

 

[Jef]

When asking for assistance, please post a complete Auto-Scan.

 

[alvinminassian]

Friday,25,April,2025,16:09:28:31387
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 25.3.1.0 (x64)  HEX-V2 CB: 0.4671.4
Data version: 20250408 DS365.0
www.Ross-Tech.com


VIN: WUADU78E88N902587   License Plate:



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Mode 01 - PID 01 : Readiness  --  Address 7E8

Number of DTCs stored: 0  --  MIL Status: MIL OFF
Misfire monitoring: Not installed.
Fuel System:  Passed
Comprehensive Components:  Passed
Catalyst monitoring:  Passed
Heated catalyst monitoring: Not installed.
Evaporative system monitoring:  Passed
Secondary air system monitoring:  Passed
A/C system refrigerant monitoring: Not installed.
Oxygen sensor monitoring:  Passed
Oxygen sensor heater monitoring:  Passed
Exhaust Gas Recirculation: Not installed.

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Mode 01 - PID 01 : Readiness  --  Address 7EA

Number of DTCs stored: 0  --  MIL Status: MIL OFF
Misfire monitoring:  Passed
Fuel System:  Passed
Comprehensive Components:  Passed
Catalyst monitoring:  Failed or Incomplete
Heated catalyst monitoring: Not installed.
Evaporative system monitoring: Not installed.
Secondary air system monitoring:  Failed or Incomplete
A/C system refrigerant monitoring: Not installed.
Oxygen sensor monitoring:  Passed
Oxygen sensor heater monitoring:  Passed
Exhaust Gas Recirculation: Not installed.

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


Mode 01 - PID 01 : Readiness  --  Address 7EA

Number of DTCs stored: 0  --  MIL Status: MIL OFF
Misfire monitoring:  Passed
Fuel System:  Passed
Comprehensive Components:  Passed
Catalyst monitoring:  Failed or Incomplete
Heated catalyst monitoring: Not installed.
Evaporative system monitoring: Not installed.
Secondary air system monitoring:  Failed or Incomplete
A/C system refrigerant monitoring: Not installed.
Oxygen sensor monitoring:  Passed
Oxygen sensor heater monitoring:  Passed
Exhaust Gas Recirculation: Not installed.

 

[alvinminassian]

When I check the fault code, I get the below response.

Friday,25,April,2025,16:14:56:31387
VCDS Version: Release 25.3.1 (x64) Running on Windows 11 x64
www.Ross-Tech.com

                Address 01: Engine       Labels: 079-910-560-BNS1.lbl
Control Module Part Number: 8E1 910 560 J    HW: 8E1 907 560
  Component and/or Version: 4.2L V8/4V FSI     ª0010
           Software Coding: 01040009180F0160
            Work Shop Code: WSC 46101 001 1048576
                      VCID: 2D07182D511697D214D-8078
Fault Codes have been Erased

1 Fault Found:
006435 - Please Check DTC Memory of ECU Number 2
               P1923 - 008 -
             Freeze Frame:
                    Fault Status: 01101000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 101550 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 780 /min
                    Load: 22.7 %
                    Speed: 0.0 km/h
                    Temperature: 72.0°C
                    Temperature: 46.0°C
                    Absolute Pres.: 940.0 mbar
                    Voltage: 13.843 V


Readiness: 0110 1101

 

[Uwe]

I don't understand how the two ECU can show different results.

Some dual-ECU setups share tasks asymmetrically. For example, I would suppose your engine only has one secondary air system, so only one of the ECUs actually monitors it.

-Uwe-

 

[Jef]

When asking for assistance, please post a complete Auto-Scan.

 

[EuroX]

Are the ecm's relfashed with modified flash files?