2018 Skoda Octavia 1.6 TDI - P06A6 + P20EE

[M. R.Ataie]

Hello everyone,

I am looking for technical guidance on a diagnostic issue and would appreciate structured input from experienced members.

Vehicle:


Skoda Octavia III (5E)

Engine: 1.6 TDI EA288

Model year: 2018

Mileage: ~198,000 km

Fault codes (stored with Bosch KTS scan tool):

- P056800 – Cruise control switch implausible signal

- P20EE00 – SCR catalyst efficiency below threshold

- P164700 – ECU variant coding / powertrain control module issue

- P06A600 – Sensor reference voltage 1 implausible signal


History:


The DTCs were read at a workshop. No parts were replaced at that time, and the fault memory was cleared. After approximately 800 km of normal driving, the MIL returned during motorway driving and has remained active since.

Current symptoms:


- No AdBlue warning or countdown


- No limp mode


- No noticeable loss of power


- Engine runs normally under all conditions


Important note:


P06A6 appears alongside P20EE and other unrelated sensor-related faults.


My request:



I am trying to identify the root cause before replacing any components.



I would appreciate if responses could focus on:


- Likely root cause hierarchy (electrical vs sensor vs SCR system)

- Known failure patterns on EA288 engines with similar DTC combination

- Recommended diagnostic sequence (what to test first, second, etc.)

I am not looking for parts replacement suggestions at this stage, but rather a logical diagnostic path to isolate the fault.
Thank you for your time and expertise.

 

[TTT]

You asking a lot tbh, can you Get Verified?

 

[M. R.Ataie]

You asking a lot tbh, can you Get Verified?

Thanks. I realize it’s quite a lot of information, but I wanted to provide as much context as possible to avoid guesswork and unnecessary parts
If you have experience with this DTC combination on an EA288, I would genuinely appreciate any guidance on a logical diagnostic path. Thank you.

 

[TTT]

Not until you are a customer of Ross Tech. Get Verified I say second and last time.

 

[Uwe]

I wanted to provide as much context as possible

The way to provide context in this forum is to post a complete Auto-Scan.

-Uwe-

 

[Viking]

Hello everyone,



Fault codes (stored with Bosch KTS scan tool):

- P056800 – Cruise control switch implausible signal

- P20EE00 – SCR catalyst efficiency below threshold

- P164700 – ECU variant coding / powertrain control module issue

- P06A600 – Sensor reference voltage 1 implausible signal

Unlikely that you'll get much assistance unless you're using VCDS, as this is Ross Techs support forum for users of that particular tool.