Codes P0491, p0492, p0456 and p0431

Good morning,

491 and 492 are for the secondary air injection system. It could be the relay or the solenoid. There are also cases that have the passages clogged with carbon. It is difficult to get to the passages as they are at the back of the motor.

the 456 is for an emission leak in the evap system. The system needs to be smoke tested to find the leak.

https://www.2carpros.com/articles/how-emission-control-systems-work

https://www.2carpros.com/articles/evap-system-code-repair

The 431 is for the catalytic converter. It is worn out and needs to be replaced.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Roy