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2018 XC90 T6 "Reduced Engine Performance" and CEL - What's going on?

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Diana O. · rep 0 · May 22, 5:20 AM · 1 replies · solved · Question

Vehicle: 2018 Volvo XC90 T6 Inscription

Hey everyone,

I'm hoping someone here has experienced this or can offer some insight. My 2018 Volvo XC90 T6 Inscription, with about 75,000 miles, has recently started throwing a "Reduced Engine Performance" message on the dashboard. This usually happens intermittently, sometimes after a cold start, and is accompanied by the Check Engine Light.

When the message appears, the car feels noticeably sluggish, almost like it's in a limp mode. I've also noticed a slightly rougher idle than usual, though it's not constant. The CEL stays on even after the "Reduced Performance" message clears itself sometimes.

I've tried restarting the car, and sometimes that clears the message temporarily, but the CEL often remains. I'm worried about potential damage or if this is a known issue with these models. Has anyone dealt with this before? What should I be looking for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:20 AM

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ClearTheCode admin answer:

The "Reduced Engine Performance" message on your 2018 Volvo XC90 T6, especially when coupled with a Check Engine Light (CEL) and rough idle, indicates that the engine control unit (ECU) has detected a significant issue requiring attention. This is a common protective measure by the vehicle to prevent further damage.

Here's what's likely happening and what steps to take:

  1. Retrieve Diagnostic Trouble Codes (DTCs): The first and most crucial step is to get the vehicle scanned for diagnostic trouble codes. While you haven't provided any specific codes, common culprits for this symptom in Volvo T6 engines include:

    • P0171/P0174 (System Too Lean Bank 1/2): Often points to a vacuum leak, faulty Mass Air Flow (MAF) sensor, or issues with the PCV system.
    • P030X (Cylinder Misfire Detected): Could be spark plugs, ignition coils, fuel injectors, or compression issues.
    • Turbocharger/Supercharger related codes: Issues with boost pressure sensors, wastegate actuators, or the supercharger clutch can directly lead to reduced performance.

  2. Common Causes:

    • Vacuum Leaks: A cracked hose or gasket in the intake system can cause unmetered air to enter, leading to a lean condition and rough running.
    • Faulty PCV System: Issues with the Positive Crankcase Ventilation system can lead to vacuum leaks or pressure problems.
    • Ignition System Components: Worn spark plugs or failing ignition coils can cause misfires, triggering the reduced performance mode.
    • Fuel System Issues: Clogged fuel injectors or a failing fuel pump can starve the engine of fuel.
    • Sensor Malfunctions: A faulty MAF sensor, oxygen sensor, or boost pressure sensor can send incorrect data to the ECU, leading to incorrect fuel-air mixture and performance issues.

  3. When to See a Shop:

    • Immediately: If the "Reduced Engine Performance" message is persistent, the engine is running very rough, or you hear unusual noises. Driving with significant performance reduction can potentially cause further damage to the engine or catalytic converter.
    • As soon as possible: Even if the message is intermittent, the underlying issue needs to be diagnosed and resolved. A qualified Volvo technician will have specialized diagnostic tools (like VIDA) to accurately pinpoint the problem and check for any relevant Technical Service Bulletins (TSBs) for your model year. They can also perform necessary software updates which sometimes resolve intermittent issues.

Do not ignore this warning, as it's your vehicle's way of telling you there's a problem that needs professional attention.

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