Can a loose fuel cap cause the check engine light to turn on in a Honda City?

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Can a loose fuel cap cause the check engine light to turn on in a Honda City?

Many Honda City owners report that their check engine light illuminates due to a loose o r cracked fuel cap. Why does this happen, and how can owners confirm if the issue is truly related to the fuel cap and not another engine o r emissions-related problem?

Sirat Ul Jinan asked on 26 Feb 2025 14:59:05 pm

1 Answer

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Car Mechanic Expert - on 26 Feb 2025 15:07:32 pm

Yes, a loose o r cracked fuel cap can indeed trigger the Check Engine Light CEL. This happens because a loose o r faulty fuel cap can create a vacuum leak in the fuel system, which can lead to incorrect readings in the vehicle’s evaporative emissions control system EVAP. The system detects the leak and registers an error code, which turns the check engine light on.

How to Confirm the Issue:

OBD-II Scanner: The best way to confirm that the check engine light is due to a faulty fuel cap is to use an OBD-II scanner to check for error codes. A common code for fuel cap issues is P0457 Evaporative Emission Control System Leak Detected.
Inspect the Fuel Cap: Physically inspect the fuel cap for cracks o r damage and ensure its properly tightened. If the CEL turns off after tightening o r replacing the cap, then the issue is most likely resolved.