P128

[Marv02]

My 2006 GMC Yukon with a 6.0 motor is throwing the engine code P128.
So far I have changed out a new Temp Sending unit, Changed the Thermostat, Changed the MAF because the Air temp is built into the MAF it self.

Has new coolant also.

The Yukon also has a 4 Core after market Aluminum radiator.

After changing out everything that should fix this issues I still getting the P128 code.

Anyone else have any ideas how fix this code from popping up.

 

[Doubeleive]

does the radiator have the restrictor in the outlet to the reservoir tank or does coolant flow pretty freely into the reservoir? what does the temp gauge read?

 

[Marv02]

I don't believe it has an restrictor in the radiator it free flowing. But this problem started after the new radiator was installed.

Temp gauge is running cooler that the stock radiator did I want to say 190 200 range and depending on the outside temperature.

But when it hot outside it runs hotter as you figure it would do.

But I have notice it takes longer to get up to temp now.

I just changed out the heater hose that go's to the coolant bottle the old one was leaking at the Y fitting.

 

[Scottydoggs]

t stat could be stuck open. or you got one thats temp is to low.

 

[Marv02]

I just did some reading on coolant restrictors make sense I still have the stock radiator I take a closer look at it and figure it out.

 

[Marv02]

t stat could be stuck open. or you got one thats temp is to low.

It a new T Stat I replaced the temp sender so might as well change the T Stat at the same time. That was not the problem I tested the old one after I had it out and tested good. the new one doing the something The restrictor make sense.

 

[Marv02]

I cut out the restrictor from the old radiator and put in the newer one hopefully this stops the codes.

 

[Marv02]

The restrictor fixed all the issues thanks.
The Yukon engine temp comes up like it use to no more check engine light.
And it running about 208 degree's back to normal.