P0128. Coolant too cool

Dross61

New member
2
0
1
Buick Ownership
2008 Lucerne
P0128 code. Engine coolant not rising in temperature fast enough. Replaced thermostat and engine code went away for over a week. During that week I ran the car 2 hrs plus on highways, 4 times. No code.

Then code came back during around town driving.

Suggestions? Higher temperature thermostat? Running cool is better than running hot, but I'd like to get rid of the check engine light.

2008 V6
 

2007LucerneCXL

Full Member
2,397
724
113
Illinois
Buick Ownership
2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Depending on a 180° or 195°, most call out for a 195° so that may be a answer. Ive seen some 192° thermostats available but can't see a big difference vs the 195°.

The other item to check is the coolant temperature sensor and especially the connector for corrosion.

Last item may be in burping the system, usually it's more of no heat in the interior, but I doubt it would cause the code if any of the other items are the issue.

The code will show up on short trips, so clear the codes, check or replace items and take for a short drive a couple of times, good luck on your project.
 

Dross61

New member
2
0
1
Buick Ownership
2008 Lucerne
Depending on a 180° or 195°, most call out for a 195° so that may be a answer. Ive seen some 192° thermostats available but can't see a big difference vs the 195°.

The other item to check is the coolant temperature sensor and especially the connector for corrosion.

Last item may be in burping the system, usually it's more of no heat in the interior, but I doubt it would cause the code if any of the other items are the issue.

The code will show up on short trips, so clear the codes, check or replace items and take for a short drive a couple of times, good luck on your project.
It has the 195. So would a 180 help? That would cause the fluid to circulate faster.
 

Merkava_4

5.7L LS1 Member
600
18
18
Clovis, CA
Buick Ownership
2000 Buick LeSabre
It's time to verify the coolant temperature with a thermometer and also find out what the computer is seeing for a coolant temperature. If the thermometer says the coolant is 195 and the computer is seeing 165, then you know the coolant sensor is lying to the computer.
 
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