P0299 on Audi
Turbo/Supercharger Underboost Condition
P0299 on Audi vehicles indicates turbo/supercharger underboost condition. Au7o has documented this code across 3 Audi models — most commonly on Q8, RS5, SQ5. P0299 means the engine computer detected an underboost condition — the turbocharger or supercharger is producing less boost pressure than the PCM expects for the given conditions. The computer compares the manifold/boost pressure sensor reading to a target based on engine load, and when actual boost falls short, it sets this code. The most common real-world cause is a leak somewhere in the intake/charge-air path. You'll typically feel reduced power or sluggish acceleration, and the engine may go into a reduced-power mode.
Common Causes of P0299
- •Boost/intake leak (cracked or loose charge-air hose or intercooler)
- •Faulty or sticking turbo wastegate or actuator
- •Stuck or clogged variable-geometry turbo vanes (VGT)
- •Faulty boost pressure or MAP sensor
- •Leaking or disconnected vacuum/boost control lines
- •Restricted air intake or clogged air filter
- •Failed boost control solenoid
- •Worn or failing turbocharger
P0299 on Audi by Model
Audi Q8(1 issue)
- 2019-2024 Q8 V6 Coolant-Pump Leak Diagnosis - TSB 2070349/42019-2024
Audi TSB 2070349/4 applies to 2019-2024 Q8 V6 TFSI vehicles with coolant loss, a coolant warning or an engine warning when the coolant pump is suspected. Audi requires precise leak confirmation: a small trace in the drip cup can be normal and dried deposits at the vacuum connection alone do not prove a leak. In individual confirmed cases, coolant can contaminate change-over valve N649 and produce P0299 as a secondary condition.
Audi RS5(1 issue)
- 2021-2024 RS5 V6 Coolant-Pump Leak Diagnosis - TSB 2070349/42021-2024
Current Audi TSB 2070349/4 applies only to 2021-2024 RS5 Coupe and RS5 Sportback V6 vehicles when the customer reports coolant loss/leak, a coolant warning or an engine warning and the workshop identifies the coolant pump as the leak source. Audi states that up to 3 ml of coolant on the pump drip cup over 100 operating hours can be normal seal lubrication/cooling. Dried coolant deposits on the vacuum connection alone are not clear evidence of a leak. Coolant contamination at change-over valve N649 may produce P0299 as a secondary condition. The bulletin does not support a universal turbocharger coolant-feed-line cracking defect or the frozen line part numbers.
Audi SQ5(1 issue)
- Mechanical Coolant-Pump Leak with Possible N649 Vacuum-System Contamination2018-2024
Audi identifies coolant loss from the mechanical coolant pump on 2018-2024 SQ5 V6 TFSI models. In some cases P0299 is logged when coolant entering the vacuum system impairs changeover valve N649. Audi cautions that a small trace on the pump drip cup can be normal and that dried deposits at the vacuum connection alone do not confirm a leak. This evidence does not establish an inherent design defect, a fixed failure mileage or a "when, not if" failure.
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View P0299 across all makes →Frequently Asked Questions
What does P0299 mean on Audi?▼
P0299 stands for "Turbo/Supercharger Underboost Condition." P0299 means the engine computer detected an underboost condition — the turbocharger or supercharger is producing less boost pressure than the PCM expects for the given conditions. The computer compares the manifold/boost pressure sensor reading to a target based on engine load, and when actual boost falls short, it sets this code. The most common real-world cause is a leak somewhere in the intake/charge-air path. You'll typically feel reduced power or sluggish acceleration, and the engine may go into a reduced-power mode. On Audi specifically, this code is documented across 3 models.
What causes P0299 on Audi vehicles?▼
Common causes on Audi: Boost/intake leak (cracked or loose charge-air hose or intercooler), Faulty or sticking turbo wastegate or actuator, Stuck or clogged variable-geometry turbo vanes (VGT), Faulty boost pressure or MAP sensor, Leaking or disconnected vacuum/boost control lines. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0299 on a Audi?▼
Repair costs vary widely depending on the root cause and specific Audi model.
Which Audi models have P0299 documented?▼
Au7o has documented P0299 on 3 Audi models: Q8, RS5, SQ5.