What starts the damage mechanism
For specified S6 Sedan MY2013–2017, 21H7 describes deposits blocking the oil-supply strainer. Insufficient turbo bearing lubrication can cause wear, followed by turbine-wheel/housing contact or shaft failure. Reported consequences include power loss and possible engine stalling.
Audi / NHTSA repository: Audi21H7 /22V178: turbocharger oil strainer safety recall
Which symptoms guide diagnosis
Audi lists EPC, MIL or oil warnings, extended cranking, rough idle and insufficient power. These require diagnosis; an indicator does not show bearing condition. Not every loss of boost can be attributed to this mechanism without checking.
Audi / NHTSA repository: Audi21H7 /22V178: turbocharger oil strainer safety recall
A useful workshop conclusion separates oil-supply condition, accessible physical turbo findings and boost-test results. Ask which components were inspected and with what results. Codes alone do not establish wheel/housing contact.
What the remedy includes
The document prescribes strainer replacement, oil change and diagnosis checking/documenting boost-system function. It does not unconditionally replace every turbo. A new-strainer entry also does not prove old bearings were unworn.
Audi / NHTSA repository: Audi21H7 /22V178: turbocharger oil strainer safety recall
Describe any confirmed mechanical turbo damage separately with examination results. Correcting insufficient lubrication and assessing its possible consequences are distinct. An invoice replacement list does not automatically establish confirmed defects.
After external impact
An accessible damaged air duct, mounting or neighbouring engine-bay assembly needs its own inspection. It does not confirm a blocked internal oil strainer. Conversely, 21H7 does not exclude separate crash damage; retain both branches in the record.
Version limits
The US table specifies certain S6 Sedan MY2013–2017. Other models and Canadian rows are separate; actual applicability needs campaign verification. This mechanism is not transferred to every engine or later S6 generation.
Audi / NHTSA repository: Audi21H7 /22V178: turbocharger oil strainer safety recall
Retain post-repair boost control results and explanations of remaining symptoms. Unopened turbo internal surfaces remain uninspected without a physical examination.
Applicability to the individual vehicle
- Defined US S6 Sedan 21H7 cohort, not all engines/generations.
- Symptoms are not physical confirmation of bearing wear on an individual car.
Primary sources
Sources checked on . Model or recall information does not establish the condition of an individual VIN.
Audi / NHTSA repository: Audi21H7 /22V178: turbocharger oil strainer safety recall
Applicability and source location
Certain US S6 Sedan MY2013–2017 under 21H7, actual VIN qualification required. Other models/Canadian rows separate; not all S6 engines.
Page 1: US scope, deposits/strainer/lubrication/bearing/wheel/shaft; page 5: owner letter; oil/strainer/boost-test remedy.
Document date: 2022-08-04. Checked: .