P0299 on Honda
Turbo/Supercharger Underboost Condition
P0299 on Honda vehicles indicates turbo/supercharger underboost condition. Au7o has documented this code across 2 Honda models — most commonly on Accord, Civic. 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. Typical repair costs on Honda range from $100 to $8,000, depending on the specific model and root cause.
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 Honda by Model
Honda Accord(1 issue)
- 1.5L Turbo Engine Oil Dilution2018-2022
The 1.5-liter turbo direct injection engine suffers from an oil dilution defect where unburned fuel enters the engine oil. This occurs when fuel is sprayed into the cylinder, drips down the cylinder walls past the piston rings, and accumulates in the oil pan. The problem is more prevalent in cold climates and with short trips. This can lead to reduced lubrication, excess engine wear, and in severe cases, engine failure.
Honda Civic(1 issue)
- 1.5T Turbocharger Coolant and Oil Line Leaks2016-2021
The 1.5L turbo Civic experiences premature failure of the turbocharger coolant feed and return hoses, and the oil feed/return lines. The banjo bolt sealing washers (crush washers) on the oil feed line compress and leak over time, causing slow oil loss near the turbo. The coolant hoses connecting to the turbo water jacket crack from heat cycling. These leaks often go unnoticed until they become significant. TSB 20-072 addresses coolant hose routing and replacement procedure for 2016-2018 models. Turbocharger CHRA (cartridge) failure from oil starvation is the worst-case outcome if oil feed line leaks undetected.
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View P0299 across all makes →Frequently Asked Questions
What does P0299 mean on Honda?▼
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 Honda specifically, this code is documented across 2 models.
What causes P0299 on Honda vehicles?▼
Common causes on Honda: 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 Honda?▼
Repair costs on Honda range from $100 to $8,000, depending on the specific model and root cause.
Which Honda models have P0299 documented?▼
Au7o has documented P0299 on 2 Honda models: Accord, Civic.