Coolant temp low code

[tommygunz12]

I got a code that said the coolant temp is consistently low. ( cant remember the code #) so i replaced the thermostat and the temp sensor and it didnt fix the issue.
The coolant temp fluctuates with the outside temp. the cooler day, the cooler the gauge reads and vise versa.

any suggestions?

thanks

2006 grand prix gt 125k miles

[Fivefingerdeathpunch]

Very possible to get a faulty thermostat.

Or you got a 180º instead of the factory 195º.

[FordMan77]

Could also be a bad coolant temp sensor, as they're known to be bad out of the box, sometimes 2 or 3 in a row before you find a good one. Did you clear the CEL after replacing the parts?

[nik12937]

The temp sensor should read a certain resistance in ohms at specific temperatures, if you have a multimeter you can verify whether or not it's the sensor.

212 F = 177 ohms
194 F = 241 ohms
176 F = 332 ohms
68 F = 3520 ohms
41 F = 7628 ohms
32 F = 9420 ohms

Those are probably the most relevant temperatures in your case since I'm not sure if you're working on this inside or outside. Operating temperature will fluctuate above and below 195 F, engine off and cold will be ambient temperature given enough time. If the sensor is good, then try checking over the wiring for any damage.

[ExLimey]

Sounds like OBD2 code P0128. I was getting this code and my coolant temps were all over depending on the outside temperature and driving conditions. I'd get an SES light every few days. I finally replaced the thermostat and it fixed my problem. When I looked it up on Google, one site said it could be these problems.

- Leaking or stuck open thermostat
- Low engine coolant level
- Insufficient warm up time
- Faulty engine coolant temperature sensor
- Engine coolant temperature sensor harness is open or shorted
- Engine coolant temperature sensor circuit poor electrical connection

Read more: http://engine-codes.com/p0128.html#ixzz3NzyufFYQ