P0420 Error: Lambda Sensor/Catalytic Converter Issue

Hello fellow DIY enthusiasts,

Unfortunately, the support team couldn't find any errors.
It's an Audi A3 with a 1.6L 2V engine.
It has already been exchanged.
- Oxygen sensor after catalytic converter.
- Spark plugs
- Activated carbon filter.
- Temperature sensor checked.
- The intake and exhaust systems were checked multiple times for leaks.
- Emission levels are perfectly fine.

The exact error is:

Code:

Adresse 01: Motorelektronik       Labeldatei: RKS\06A-906-033-BGU.lbl    Steuerger‰t-Teilenummer: 06A 906 033 EH   Bauteil und/oder Version: SIMOS71 1.6l 2V     9429                  Codierung: 0000071             Betriebsnummer: WSC 06314 000 00000                       VCID: 69DC1836401440562C3-803C 1 Fehler gefunden: 16804 - Katalysatorsystem; Bank 1             P0420 - 006 - Wirkung zu gering - Sporadisch              Freeze Frame:                     Drehzahl: 3808 /min                     Hex Wert: 0x0079                     Geschwindigkeit: 120.6 km/h                     Temperatur: 624.0°C                     Drehzahl: 3808 /min                     Hex Wert: 0x007C                     Geschwindigkeit: 120.6 km/h                     Temperatur: 616.0°C

Unfortunately, the error is not consistent but occurs sporadically. There is no correlation with external temperature or other factors.
The solutions I found using "google" didn't necessarily help me much.
Has anyone else experienced this error?

Thank you very much for your efforts!


P.S.: I'm not really an expert on gasoline/petrol.

Quote:

Unfortunately, the error is not constant but sporadic.

When and how often does the error occur? What is the mileage?

Hello,

The error occurs every 200-400 kilometers after being cleared.
The car has 135,000 kilometers on the odometer, but it's not driven for short distances.

SG Christian.

Check the lambda value after the catalytic converter while driving; it might indicate that the catalytic converter is not functioning correctly anymore.

Hello,

I've already checked the values, but unfortunately, no error occurred during these trips.
I've now completed the readiness assessment.
The result is that a new error has been introduced.

Code:

18628 - Bank 1 Sonde 1             P2196 - 006 - Signal zu fett              Freeze Frame:                     Drehzahl: 1984 /min                     (keine Einheit): 0.99                     Spannung: 2.040 V                     Spannung: 0.780 V Readiness: 0010 1101

What do you think, probe or catalytic converter?
What else can be checked?

Sure, here's the translation:

"SG" can have different meanings depending on the context. It could stand for "Spielgemeinschaft," which is a German term for a sports club or association that combines players from multiple teams or organizations. Alternatively, it could refer to "Säkularkantor," a type of church musician who does not hold religious beliefs. Finally, "SG" might be an abbreviation for "Sonstige," meaning "other" or "miscellaneous."

T3Surfer wrote:

Check the Lambda value after the catalytic converter while driving.

servusssss wrote:

I've already looked at the values, but unfortunately, no error occurred during these trips.

You should look at the lambda value in the measurement block and see if it's running too fat.

It doesn't matter if an error is accidentally entered while you're looking at it.

Hi.

Quote:

You should look at the lambda value in the measurement block and see if the engine is running too rich.

I already checked the values during the ride, and I didn't notice anything unusual or any error messages.
This occurred during the readiness test.
I looked at the documents with identification numbers MWB 001-031-037; are these the correct ones?

Sure, here's the translation:

"SG" can have different meanings depending on the context. It could stand for "Spielgemeinschaft," which is a German term for a sports club or association that combines players from multiple teams or organizations. Alternatively, it could refer to "Säkularkantor," a type of church musician who does not hold religious beliefs. Finally, "SG" might be an abbreviation for "Sonstige," meaning "other" or "miscellaneous."

Okay, just create a log file and upload it here.

"For vehicles with higher mileage, a P0420 code usually indicates an issue with the catalytic converter or the upstream oxygen sensor, assuming everything else is in good working order."

Here's an explanation of how you can get to the bottom of the problem.
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

It is important to consider both lambda sensors simultaneously. The error may not be registered immediately, but it can be easily identified by observing the trend of the lambda sensor voltage over time.

Hi,

Here's another log, unfortunately with a lot of partial load data.
I can't see anything, but I know very little about the Lambda regulations.

Sure, here's the translation:

"SG" can have different meanings depending on the context. It could stand for "Spielgemeinschaft," which is a German term for a sports club or association that combines players from multiple teams or organizations. Alternatively, it could refer to "Säkularkantor," a type of church musician who does not hold religious beliefs. Finally, "SG" might be an abbreviation for "Sonstige," meaning "other" or "miscellaneous."

It actually looks quite good, and the adjustments are also fine.

It looks like an intermittent problem.

Hello everyone,

After a brief inquiry via private message, here is the unfortunately not very pleasant solution to the problem.
After replacing the catalytic converter, there was a period of calm. However, after about 3000 km, the problem reappeared.
The car was then sold to a dealer.

In summary, the error could not be resolved. Under the table, a new software solution for the MSG was recommended.

Sure, here's the translation:

"SG" can have different meanings depending on the context. It could stand for "Spielgemeinschaft," which is a German term for a sports club or association that combines players from multiple teams or organizations. Alternatively, it could refer to "Säkularkantor," a type of church musician who does not hold religious beliefs. Finally, "SG" might be an abbreviation for "Sonstige," meaning "other" or "miscellaneous."