Why Does the Hyundai Santro Fail Emission Tests o r Check Engine Light Come On?

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Why Does the Hyundai Santro Fail Emission Tests o r Check Engine Light Come On?

Some Santro vehicles fail government emission tests o r trigger the check engine light. What engine o r sensor faults commonly lead to emission failures, and which parts should owners inspect to maintain compliance with local emission standards?

Talha Kyanii asked on 03 Dec 2025 17:12:33 pm

1 Answer

9 views |

Gari Master - on 03 Dec 2025 17:15:49 pm

Emission test failure o r the check engine light is often related to sensor o r engine inefficiencies.

Common Causes

Faulty oxygen O2 sensor:
Gives incorrect air–fuel mixture readings to the ECU.

Dirty Mass Air Flow MAF o r MAP sensor:
Causes poor fuel metering and higher emissions.

Clogged catalytic converter:
Cannot convert harmful gases effectively, increasing emissions.

Engine misfire o r worn spark plugs:
Leads to incomplete combustion.

Exhaust leaks:
Unmetered air in the exhaust can trigger emission faults.

Solutions

Replace o r clean O2 and MAF/MAP sensors.

Inspect and clean o r replace the catalytic converter if blocked.

Replace spark plugs and ignition components as needed.

Fix exhaust leaks.

Reset ECU after repairs to clear the check engine light.