P0299 on Renault: How to Diagnose & Fix
Turbo/Supercharger Underboost Condition
1 Renault model · 1 documented issue · 1 critical · $1,200-$2,800 repair
P0299 on Renault by model: symptoms, diagnosis and fix
The K9K 1.5 dCi diesel in the Mégane II and III suffers well-documented turbocharger failures caused by oil starvation: extended oil-change intervals let carbon sludge block the narrow turbo oil feed pipe and sump pickup strainer, starving the turbo bearings. A sticking EGR valve raising exhaust gas temperatures accelerates the bearing failure. Owners report sudden loss of power, a whining turbo and blue smoke; if debris from the failed turbo enters the engine, the bill escalates sharply.
Common Symptoms
- Sudden loss of power / limp mode, top speed limited to around 60 mph
- Whining or siren noise from the turbo
- Blue smoke from the exhaust
- Excessive oil consumption or oil smell near the turbo
- Underboost fault codes logged
How to Fix
Replace the turbocharger together with new oil feed and return pipes, drop the sump to clean the oil pickup strainer, and perform an oil and filter flush — fitting only the turbo guarantees a repeat failure. Stick to shortened oil-change intervals (10,000 km or less) with the correct low-ash C3 oil.
Sources for this issue (5)
- Loss of power in 1.5Dci — The Mégane II Owners' Club (turbo oil starvation warning, 2004 Mégane II)forum
- Megane 15dci Turbo failure — Independent Renault Forumsforum
- Common problems with the Renault Megane — WhoCanFixMyCar (1.5/1.9 dCi injector/turbo/EGR problems)article
- 1.5 dCi engine: most common problems — Autoricambi Tritellaarticle
- Renault Megane 1.5 dCi 2013 turbocharger failure case study (seizure from degraded oil) — Best Turbosarticle
P0299 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0299 mean on a Renault?
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 Renault it is documented across 1 model: Megane.
What are the most common causes of P0299?
The most common causes of P0299 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0299 on a Renault?
Published repair estimates on Renault range from $1,200 to $2,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.