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2018 Q50 3.0T - Loss of Power and Check Engine Light (P0299)

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Robert C. · rep 0 · May 22, 5:04 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 Red Sport 400

Hey everyone,

I'm having an issue with my 2018 Infiniti Q50 Red Sport 400. Recently, I've noticed a significant loss of power, especially when accelerating onto the highway or trying to pass. It feels like the turbos aren't kicking in properly, and the car just struggles.

Along with the power loss, the check engine light came on. I used my OBD-II scanner and pulled a P0299 code, which indicates an 'Engine Underboost' condition. I've heard this can be a common issue with the VR30DDTT engine, but I'm not sure where to start troubleshooting.

Has anyone else experienced this with their Q50? What was the cause, and what was the fix? I'm trying to gather some information before I take it to the dealership or an independent shop. Any advice would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:04 AM

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ClearTheCode admin answer:

The P0299 'Engine Underboost' code on your 2018 Infiniti Q50 Red Sport 400 with the VR30DDTT engine is a common concern and points directly to an issue with your turbocharging system not producing the expected boost pressure. Addressing this promptly is important to prevent further issues.

Here are the common causes and steps:

  1. Vacuum Leaks: The most frequent culprit. Inspect all vacuum lines connected to the turbo system, wastegate actuators, and boost control solenoids. A small crack or loose connection can lead to significant boost loss.
  2. Wastegate Actuator Issues: The wastegate controls exhaust flow to the turbo. If an actuator is stuck open, faulty, or has a compromised vacuum line, boost will be lost. Check for proper movement and any signs of damage.
  3. Boost Control Solenoid Failure: This solenoid regulates the vacuum to the wastegate actuators. If it's failing, it won't properly control boost pressure. Testing its operation with a vacuum gauge or diagnostic tool can confirm this.
  4. Charge Air Cooler (Intercooler) Leaks: Leaks in the intercooler or its piping can allow boost pressure to escape before reaching the engine. Visually inspect the intercooler and all associated hoses for cracks or loose clamps.
  5. Turbocharger Failure: While less common than the above, a failing turbocharger (e.g., worn bearings, damaged compressor wheel) can also cause underboost. Listen for unusual noises from the turbos.

When to See a Shop:

If you're not comfortable performing detailed inspections of vacuum lines, testing solenoids, or if visual inspection doesn't reveal an obvious problem, it's best to take your Q50 to a qualified Infiniti dealership or an independent shop specializing in Infiniti vehicles. They have specialized diagnostic tools to pinpoint boost leaks, test turbocharger performance, and accurately diagnose wastegate and boost control system components. Driving with a persistent underboost condition can lead to reduced engine performance and potentially affect fuel economy or other engine components over time.

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