I have the engine codes P0505 and P0170 on my 2000 Mitsubishi, what could be the problem?

Question

I have the engine codes P0505 and P0170 on my 2000 Mitsubishi Galant, what could be the problem? The vehicle is idling rough

Answer 1

P0505 Idle control system malfunction

P0170 Fuel trim malfunction Bank 1

Vacuum leak with these two type of code in a combination , a vacuum leak will affect the idle performance where it can not be controlled  and will lean out the fuel trim, one area to check will be the EGR system

Answer 2

P0505 MITSUBISHI Code - Idle Control System Malfunction
Read more: https://www.autocodes.com/p0505_mitsubishi.html

P0170 MITSUBISHI Code - Fuel Trim Malfunction Bank 1
Read more: https://www.autocodes.com/p0170_mitsubishi.html