Need Help

[Z-56 Hoe]

ok so last night i was driving ang got on her a little and the check engine light came on again it is showing two Codes : P0401 and P1258. Now I belive the 1258 is a cooling code. Last Friday leaving the mall My Tahoe over heated and so Sat Morning I changed the Thermstate and that seemed to Fix that. so I cleared it. But Now I have Both P0401 and P1258 on a 2001 Tahoe WTF are they and do they mean?

 

[RobertWYoung]

P1258 is Engine Coolant Overtemperature - Protection Mode Active
P0401 is Insufficient EGR Flow


P1258 -> The PCM uses the ECT sensor to monitor the engine for an over temperature condition. This condition occurs when the coolant temperature is above 132°C (270°F). When an over temperature condition is present, DTC P1258 will set. The PCM will disable two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.

http://www.obd-codes.com/p0401

 

[Z-56 Hoe]

Thank You. My coolent temp seems to be good now tho. so what would couse P1258 to come back?

 

[Z-56 Hoe]

well?