A1/S1 Audi A1 1.5 TFSI (EA211) – Cylinder 4 damage after possible misfuel

[crazy69100]

Hello everyone,

I’m seeking some technical insight regarding an unusual engine failure on my Audi A1 Citycarver 1.5 TFSI (150hp, 2022).

About 12 days after purchase (imported from Germany to France), the car showed a flashing engine light, then a message “Workshop! Please switch to manual mode.” The car lost power and stopped shortly after — no smoke, no noise, no oil loss.

A diagnostic scan showed:

• P30C000 – Fuel quality insufficient (appeared at 05:10 a.m.)
• P017100 – Fuel mixture too lean (Bank 1)

An endoscopic inspection found:

• Cyl 1: clean, normal
• Cyl 2-3: oily traces
• Cyl 4: scratched with piston edge erosion
  Also, the turbocharger was declared defective, but without explanation.

The official report concluded it was due to “fuel error (possible diesel)” because the tank was filled around 4:45 a.m., and the fault appeared around 5:10 a.m.

However, I find it hard to believe that a small quantity of diesel (about €25 worth) could destroy only one cylinder, while the others remain normal.

I would really appreciate technical opinions from anyone familiar with EA211 or 1.5 TFSI engines:

• Could such localised piston/cylinder damage be caused by a brief misfuel?
• Could turbo failure or mixture imbalance explain this type of damage instead?

Thank you so much for your help — I just want to understand what could really have happened before taking legal steps.

 

[Centurion]

Sorry that this happened. Thanks for sharing. If diesel is put into a petrol engine, the risk of premature ignition is high. It can happen in one or several cylinders.

In a nutshell it’s volatility versus control and expected combustion.

 

[crazy69100]

Thank you very much for your detailed explanation.

I really appreciate it.

Do you think that only 14.6 litres of Excellium diesel in a 40-litre petrol tank could really cause that much damage — especially without the engine stalling immediately?

 

[Serpens]

Yes, absolutely. Sorry to hear about your misfortune but this can happen in an instant.