Question

2001 Pontiac Sunfire 2.2L with engine code P1879, how do I fix code p1879?

Answer 1

P1879 Transmission transfer case disengage solenoid open circuit

This code you dont have to fix your not equipt with it, But if its P1870 the fix is to replace the whole valve body, This is a wear in the bore of the control valve body,as a result there is no TCC apply.

Answer 2

P1870 PONTIAC Code - Transmission Component Slipping
Read more: https://www.autocodes.com/p1870_pontiac.html