Print Error P1297 & P1093: Troubleshooting Guide

Hello,

My Polo with the EA113 (CDL) engine is starting to show some problems at just 12,000 km.

After a few days of inactivity and a cold start at approximately -4°C engine temperature, the idle speed initially fluctuated significantly between about 800 and 1400 rpm. Starting was almost normal, but there were occasional hard jolts below 1500 rpm. Even after a few minutes of driving, the idle speed was still not stable and continued to fluctuate (though slightly less intensely than immediately after starting).
Eventually, when the engine was warm, all the problems disappeared. Even full-throttle data logs, reaching the rev limiter, appeared completely normal.
Only in the file system.

Code:

2 Fehlercodes gefunden: 004759 - Verbindung Lader-Drosselklappe P1297 - 001 - Druckabfall Umgebungsbedingungen: Fehlerstatus: 01100001 Fehlerpriorität: 2 Fehlerhäufigkeit: 1 Verlernzähler: 255 Kilometerstand: 12564 km Zeitangabe: 0 Datum: 2039.14.00 Zeit: 11:16:02 Umgebungsbedingungen: Drehzahl: 1445 /min Last: 30.6 % Geschwindigkeit: 31.0 km/h Temperatur: 9.0°C Temperatur: -3.0°C Druck: 990.0 mbar Spannung: 14.605 V 004243 - Bank 1; Kraftstoffbemessungssystem 2 P1093 - 008 - Fehlfunktion - Sporadisch Umgebungsbedingungen: Fehlerstatus: 00101000 Fehlerpriorität: 2 Fehlerhäufigkeit: 1 Verlernzähler: 255 Kilometerstand: 12569 km Zeitangabe: 0 Datum: 2039.14.00 Zeit: 11:21:23 Umgebungsbedingungen: Drehzahl: 1492 /min Last: 27.0 % Geschwindigkeit: 40.0 km/h Temperatur: 53.0°C Temperatur: -5.0°C Druck: 1000.0 mbar Spannung: 14.732 V

The next cold start the following morning, with a temperature of around -3°C, was also normal.
Does anyone here know the symptoms and possible causes?


Here's something else that I don't like as much:
After cold starts in winter, the engine gradually becomes "audibly rougher" under load compared to before, meaning that one cylinder produces a soft "thumping" sound during acceleration. I notice it most clearly in lower gears between 1500 and 2000 rpm. The noise completely disappears when coasting, and as the engine temperature increases, it becomes quieter and eventually vanishes altogether.
The engine doesn't misfire and otherwise runs normally and without any noticeable issues, except for the one incident mentioned above.
Oil consumption is present (approximately 0.2 liters per 1000 km), but in my opinion, it's not yet a cause for concern.

What could be the cause of the acoustic imbalance in the cylinders, which, as mentioned before, wasn't so noticeable earlier? Could it be that a connecting rod bearing or piston pin is already starting to fail? Or is it more likely a piston tilt that is correcting itself as all components reach their normal operating dimensions when warm?

Cause:
Positive Crankcase Ventilation (PCV) valve - That's how it usually starts - Eventually, the engine won't run smoothly anymore, even when warm.

@Blackfrosch
"Are you referring to the unusual stuttering and lag that we've seen so far?"
Or the uneven cold start noise under load?

The speed fluctuations and the two error entries.