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Check Engine Light and EyeSight Disabled on 2021 Crosstrek

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Angela R. · rep 0 · May 22, 3:13 AM · 1 replies · solved · Question

Vehicle: 2021 Subaru Crosstrek Limited

Hello everyone,

I'm having a weird issue with my 2021 Subaru Crosstrek Limited. The Check Engine Light (CEL) just came on, and immediately after, my EyeSight system (adaptive cruise, lane keep assist) disabled itself. The dashboard shows a message 'EyeSight Disabled' and the pre-collision braking system is also off. I haven't noticed any performance issues with the car itself.

I've heard that sometimes a loose gas cap can cause the CEL and disable EyeSight on Subarus. Is this true for a 2021 model? I checked my gas cap and it seemed tight, but I re-tightened it just in case. What else could cause this combination of warnings?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:13 AM

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ClearTheCode admin answer:

You're absolutely right; a Check Engine Light (CEL) on a modern Subaru, even for something seemingly minor, will often disable the EyeSight system. This is a safety feature, as EyeSight relies on various engine and vehicle sensors to function correctly. If the ECU detects an issue that could affect vehicle dynamics or sensor accuracy, it will disable advanced safety systems.

  1. Loose Gas Cap (EVAP System): This is indeed one of the most common culprits for a CEL on Subarus, and it will disable EyeSight. Even if it felt tight, re-tightening it firmly (until it clicks several times) is the first step. Drive the car for a few cycles, and the light may clear itself. The code associated with this is typically a P0455 (Large EVAP Leak) or P0456 (Small EVAP Leak).
  2. Other EVAP System Leaks: Beyond the gas cap, other components of the Evaporative Emission Control (EVAP) system can develop leaks, such as the purge valve, vent valve, or hoses. These will also trigger a CEL and disable EyeSight.
  3. Oxygen Sensors/Catalytic Converter: While you haven't noticed performance issues, a failing O2 sensor or catalytic converter (P0420, P0133, P0171, etc.) will trigger a CEL and disable EyeSight. These issues can sometimes be subtle at first.
  4. Mass Air Flow (MAF) Sensor: A dirty or failing MAF sensor can cause incorrect air-fuel mixture readings, leading to a CEL and potentially affecting engine performance, which in turn disables EyeSight.

When to See a Shop:

  • If the CEL and EyeSight disabled message don't clear after a few drive cycles (after ensuring the gas cap is tight), it's best to have a shop scan the vehicle for specific diagnostic trouble codes (DTCs). Knowing the exact code is crucial for proper diagnosis.
  • A professional can perform a smoke test on the EVAP system to pinpoint leaks, or diagnose sensor failures that might not be immediately obvious. Ignoring a CEL, even if the car seems to drive fine, can lead to more significant issues down the road and keeps your safety systems offline.
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