What is the code for the f150 Ecoboost Underboost?

The code is P0299.

Underboost occurs when the engine's boost pressure from the turbocharger is lower than what the engine control module expects, which can result in reduced power and increased fuel consumption. In Ford F-150 EcoBoost models, P0299 is the standard diagnostic trouble code used to signal this condition. This article explains what P0299 means for the F-150, common causes, diagnostic steps, and how to address the issue.

What P0299 means for the F-150 EcoBoost

P0299 is a generic OBD-II code that Ford applies to indicate the turbocharger is not producing the expected boost. For EcoBoost-powered F-150s, this often triggers a drop in throttle responsiveness and may illuminate the check engine light. The exact symptoms can vary depending on engine size (2.7L, 3.5L), model year, and driving conditions.

When the code appears with additional data

In many cases, the OBD-II scanner will display a freeze-frame snapshot showing boost pressure, RPM, engine load, and sensor readings at the time the condition was detected. A live data readout can help identify whether boost pressure is consistently low, fluctuating, or momentarily dropping under load.

Common causes of Turbocharger Underboost on EcoBoost F-150

Below is a list of frequent culprits that can trigger P0299 on Ford F-150 EcoBoost models. The list highlights issues you or a technician should consider during diagnosis.

• Vacuum or boost leaks in the intake system (hoses, intercooler lines, throttle body gasket) that reduce the amount of air reaching the engine.


• Faulty or stuck turbocharger wastegate actuator or boost control solenoid causing the turbo to not open fully or quickly enough.


• Damage or leaks in the intercooler or charged-piping allowing pressurized air to escape before reaching the intake manifold.


• Defective boost pressure sensor or MAP sensor giving incorrect readings to the ECU, or a failing ECU calibration.


• Exhaust restrictions such as a clogged catalytic converter or restricted exhaust path increasing backpressure and reducing boost.


• Oil contamination or worn turbo bearings leading to degraded turbo performance.


• Vacuum-related issues from the PCV system or cracked vacuum lines affecting manifold pressure readings.

These are not exhaustive; the actual cause may be a combination of factors. A professional diagnostic approach helps isolate the root cause and determine the appropriate repair.

How to diagnose and address P0299 on a Ford F-150 EcoBoost

Follow these steps to systematically diagnose and address a P0299 underboost condition. This is a high-level guide; if you are not comfortable performing these checks, consult a qualified mechanic.

1. Retrieve multiple fault codes and freeze-frame data with an OBD-II scanner to confirm P0299 and capture accompanying sensor readings.


2. Check for obvious boost leaks by performing a thorough visual inspection of all intercooler hoses, charge pipes, clamps, and the intercooler for cracks or damage.


3. Perform a smoke test on the intake system to reveal small leaks that may not be visible.


4. Inspect the turbocharger and wastegate actuator for proper movement. Ensure the wastegate opens and closes as commanded and there are no sticking components.


5. Test the boost control solenoid and related vacuum lines for cracks, leaks, or improper operation.


6. Check the intercooler for blockages or internal leaks that could reduce effective boost pressure.


7. Make sure there is no exhaust restriction; inspect the catalytic converter for signs of clogging and verify there are no exhaust blockages upstream of the turbo.


8. Verify sensor readings (boost pressure sensor or MAP) are within specification and consider replacing faulty sensors if readings are inconsistent with real-world measurements.


9. Scan for software updates or TSBs from Ford that address boost issues for your specific model year and engine, and perform updates if available.

After addressing the root cause, recheck the system with the scanner and perform test drives to ensure boost levels are within spec under various loads and RPMs.

Summary

P0299 is the code most commonly associated with Turbocharger/Supercharger Underboost on Ford F-150 EcoBoosts. Diagnosing and fixing it involves checking for leaks, worn components, faulty sensors, and possible exhaust restrictions, followed by verifying boost with live data after repairs.

Key takeaways: P0299 signals underboost in EcoBoost F-150s; systematic inspection of intake/vacuum leaks, turbo/wastegate operation, intercooler integrity, sensors, and exhaust flow is essential, followed by verification of boost restoration after repairs.

What is the code P0299 on a Ford F150 EcoBoost?

The Ford P0299 code indicates a turbocharger underboost condition, meaning the engine isn't generating the expected boost pressure. Common causes include boost leaks from loose or cracked hoses and intercooler issues, a faulty wastegate or bypass valve, or a clogged air filter. Addressing these issues often involves inspecting and securing all intake and boost-related hoses and clamps, checking the turbo wastegate actuator, and potentially replacing the air filter.
 
Common causes

• Boost leaks: Leaks can occur in the intake, intercooler, or charge pipes, often caused by cracked hoses, loose clamps, or damaged seals. 
• Faulty wastegate or bypass valve: The wastegate or bypass valve may stick open or leak, causing a loss of boost pressure. 
• Clogged air filter: A dirty or clogged air filter restricts airflow to the turbo, preventing it from building sufficient pressure. 
• Turbocharger problems: Though less common, the turbocharger itself may be failing. 
• Other issues: Low engine oil pressure or problems with vacuum control valves can also lead to this code. 

This video explains the P0299 code on a Ford F-150 EcoBoost and demonstrates how to diagnose it: 55sRedline DetectionYouTube · Aug 6, 2020
Diagnosis and fixes

• Inspect for leaks: Visually check all hoses and pipes in the air intake and boost system for cracks, damage, or loose connections. Pay close attention to the charge pipe connecting to the throttle body. 
• Check components: Inspect the turbocharger wastegate actuator for proper movement and vacuum supply. Also, check the boost bypass valve for proper operation. 
• Replace air filter: A simple and inexpensive solution is to check and replace the engine air filter, as a clogged filter is a very common cause. 
• Consider other parts: If the above steps don't solve the problem, a professional mechanic can check other components like the boost pressure sensor or look for internal engine issues. 

This video demonstrates how to fix a P0299 code by replacing a faulty bypass valve: 1mTunnell Custom GarageYouTube · Jun 10, 2023

How do I fix the code P0299 on my Ford?

Open the hood, locate the air filter, and check its condition. If it's dirty, replace it. This is one of the easiest and cheapest ways to fix a P0299 code.

What causes turbo underboost code?

A turbo underboost code is typically caused by leaks in the intake system, such as in the charge pipes or intercooler, or issues with the turbocharger itself, including a malfunctioning wastegate or worn turbo. Other common causes include a clogged air filter, a faulty boost pressure sensor, or problems with the Exhaust Gas Recirculation (EGR) system.
 
This video explains common causes and fixes for P0299 code: 59sHVAC Mechanic YouTube · Jan 28, 2024
Air leaks and restrictions 

• Boost leaks: Cracks or loose connections in the charge pipes, intercooler hoses, or intake manifold can cause pressurized air to escape before it reaches the engine. 
• Clogged air filter: A dirty air filter restricts the amount of air that can flow into the turbo, forcing it to work harder and potentially causing underboost. 
• Restricted exhaust: A clogged catalytic converter or Diesel Particulate Filter (DPF) can create backpressure, preventing the turbo from spooling up correctly. 
• Intercooler issues: Leaks or blockages within the intercooler can also reduce performance. 

Turbocharger and wastegate problems 

• Faulty wastegate/actuator: The wastegate controls the amount of exhaust gas that flows through the turbo. If it's stuck open, too much gas will bypass the turbine, leading to a loss of boost. The actuator that controls the wastegate can also fail. 
• Worn turbo: The turbo's internal components, such as the bearings or blades, can wear out or become damaged, preventing it from generating sufficient boost. 
• EGR system defects: Problems with the Exhaust Gas Recirculation (EGR) system can affect airflow and impact boost pressure. 

This video shows how a faulty wastegate can cause underboost: 58s8020 AutomotiveYouTube · Oct 14, 2025
Sensor and control issues

• Faulty boost pressure sensor: A malfunctioning sensor may provide incorrect readings to the engine control module (ECM), even if the boost pressure is normal. 
• Failed diverter valve: This valve can fail, causing a loss of boost pressure. 
• Low oil pressure: Insufficient oil pressure can prevent the turbo from operating at its optimal performance level. 

How much does it cost to fix a P0299 code?

The repair cost for a P0299 code can range from \$50 to over \$3,000, depending on the specific cause, which can include a simple fix like a new air filter or a major repair like replacing a turbocharger. A diagnostic check is essential to identify the exact problem before estimating the repair cost, as the solution could be as simple as tightening a hose or replacing the air filter, or it could be a much more expensive turbo replacement. 
Potential repair costs

• Low-cost fixes ($50 - $200):
  • Replacing a clogged air filter. 
  • Repairing minor boost leaks from loose or cracked hoses. 
  • Cleaning or replacing sensors. 
• Moderate to high-cost fixes ($800 - \$3,000+):
  • Replacing the turbocharger or a faulty wastegate solenoid, which can range from \$800 to \$1,800 or more for the part and labor. 
  • Replacing the intercooler and piping if they are contaminated or damaged, which can add significantly to the cost, sometimes pushing the total well over \$2,000. 
  • In rare cases, a complete engine replacement could be necessary, with costs potentially reaching \$3,000 or more. 

Before you get a repair quote

• Get a diagnosis: Have a mechanic perform a diagnostic test to determine the exact cause of the P0299 code, as it could be a simple and inexpensive fix. 
• Ask for a breakdown: If the repair estimate is high, ask the shop for a detailed breakdown of the parts and labor involved. 
• Consider the vehicle: The total repair cost can be influenced by the specific vehicle you own. For example, a P0299 code on a Chevy Cruze might have different cost variables compared to other makes and models.