P0299 on Fiat: How to Diagnose & Fix
Turbo/Supercharger Underboost Condition
2 Fiat models · 2 documented issues · $100-$1,200 repair
P0299 on Fiat by model: symptoms, diagnosis and fix
The charge piping between the turbocharger and intercooler develops leaks at the silicone coupler connections, causing loss of boost pressure and reduced power. The issue is more common on the Abarth tune.
Common Symptoms
- Loss of power under boost
- Whooshing or hissing sound
- Check engine light
- Boost gauge reading low
How to Fix
Inspect and retighten all intercooler piping clamps. Replace any cracked or deteriorated silicone couplers. Upgraded aftermarket piping kits with T-bolt clamps are recommended.
Sources for this issue (1)
The turbocharger wastegate develops a rattle or fluttering noise at idle and low RPM due to wear in the wastegate actuator linkage. The noise is more pronounced when the engine is cold.
Common Symptoms
- Rattling at idle
- Flutter sound on deceleration
- Metallic tapping from turbo
- Reduced boost pressure
How to Fix
Replace the wastegate actuator or adjust the wastegate rod length. In severe cases, the turbocharger assembly may need replacement if internal wastegate components are worn.
Sources for this issue (1)
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 Fiat?
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 Fiat it is documented across 2 models: 124 Spider, 500L.
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 Fiat?
Published repair estimates on Fiat range from $100 to $1,200 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.
Looking for P0299 on a different make?
View P0299 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.