Check Engine Light: P0128 Code

**mecsimm** · 04-14-2013

I have a 2005 GP. Recently, the check engine light came on. I had it scanned, and it showed P0128: coolant temp below regulated temp. I do remember that it came on during a cool morning (45F). Is it possible the code will reset, now that temps are warmer ? Is there a certain number of engine starts that will clear it ?

Is there a way to clear the codes quicker, so I can see if it comes back ?

And lastly, is there a way to retrieve trouble codes similar to the way that older OBD-1 cars could ? You woul jumper the diagnostic terminal and count flashing lights for the number of the code.

**Scottydoggs** · 04-14-2013

temp sensor is under the t stat housing, bottom of the lim, just change it. look over the wires first tho, they could be bad.

**02NavyBlue** · 04-14-2013

I believe that code will reset, I had it on an impala with the 3.8 and it was stored as previous codes, but not a current code.
Use an OBD II scan tool to retrieve codes. They run as low as $50 to get a simple code reader, but you can go to an auto parts store and they will read codes for free.
No jumper wire techniques on OBD II, just a scan tool.

I fixed this issue by putting in a new thermostat (Also did a cooling system flush and new rad cap, the t-stat is what fixed the problem)

**kingspadeshan** · 07-14-2013

Originally Posted by Scottydoggs

temp sensor is under the t stat housing, bottom of the lim, just change it. look over the wires first tho, they could be bad.

Hey Scotty u've helped me on the trans forum and now I have a new problem. P0128 code just came on. From what I hear its a bad thermostat? If so what brand/temp do I swap it with? Autozone says a 195 degree duralast? Is that correct?

**Scottydoggs** · 07-14-2013

OBD-II Trouble Code: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) looks like a temp sensor.

if your gonna change the t stat get a 195. i have no fav brand.

**02NavyBlue** · 07-14-2013

Originally Posted by Scottydoggs

OBD-II Trouble Code: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) looks like a temp sensor.

All it's saying is it's detecting that the system took too long to warm up. "The intent of the P0128 code is to indicate a faulty thermostat."

Originally Posted by kingspadeshan

Hey Scotty u've helped me on the trans forum and now I have a new problem. P0128 code just came on. From what I hear its a bad thermostat? If so what brand/temp do I swap it with? Autozone says a 195 degree duralast? Is that correct?

Stant is a very common brand for thermostats, if you go with them get their superstat version. It's a few bucks more but is identical to oem.

**kingspadeshan** · 07-14-2013

Thanks Blue

**kingspadeshan** · 07-14-2013

Originally Posted by 02NavyBlue

All it's saying is it's detecting that the system took too long to warm up. "The intent of the P0128 code is to indicate a faulty thermostat."

Stant is a very common brand for thermostats, if you go with them get their superstat version. It's a few bucks more but is identical to oem.

Is it safe to drive the car for a day or two without damaging anything ?