When the oxygen sensor heater circuit is not functioning properly, the oxygen sensor cannot reach its optimal operating temperature, which affects its ability to accurately detect the oxygen content in the exhaust gas. This can lead to an incorrect fuel mixture, which can cause the car to run inefficiently and produce excessive emissions.
To resolve the issue, it is recommended to inspect and replace the left-hand oxygen sensor and its wiring if necessary. This should restore the oxygen sensor heater circuit to proper operation, allowing the oxygen sensor to function properly and the car to pass state emissions tests.
It's important to note that other factors can also contribute to a car failing emissions tests, such as issues with the catalytic converter, exhaust system, or fuel injector system. If the fault code FF67 persists after replacing the oxygen sensor and its wiring, further diagnostics may be necessary to identify and address the root cause of the emissions issue.
