[Trent_]

I currently have a 2016 Chevy Cruze Limited LS 1.8L with 106k miles. A few weeks ago I had a P0128 error code show up so I replaced both of the ECT sensors. Since then I will still intermittently get this error (a few times a week when driven daily). Along with this, I noticed that when I have my ODB reader out the temperature gauge stops at 85C and will not go any higher. On my reader, it has gone as high as 105C before I shut off the car to let it cool without the needle moving past the tick before the middle of the gauge. If I am driving the gauge will move below 85C if it cools off just never above it. Initially, I thought the fan was bad but it runs intermittently (on for a few seconds then off for 15-30 seconds) when the AC is on just not from the engine getting near overheating temperatures. I have checked all of the fuses and relays and they all were good. At this point, I am not sure what to continue checking, so if anyone has any ideas of where to go that would be wonderful.

Summary:

• The coolant temp gauge won't go above 85C despite ODB scanner reading up to 105C

Attempted Fixes:

• Replaced both ECT sensor
• Check all relays and fuses involved in the system
• Made sure everything has a solid connection (no loose plugs)

Additional Issues:

• Fuel economy is 25-26MPG overall with about 85% of driving on highway and interstate
• Burns about 1-2 quarts of oil in between changes
• P0128 and P0442 error codes are thrown a few times a week
• Radiator fan only runs when AC is on and only does so for a few seconds then is off for 15-30 seconds

 

[CRUISE-CRUZE]

Hello to you too!

 

[Johnny B]

Well 1.8L engines are not my thing, but the 1.4L really need OEM sensors or they go nuts. Were the replacement ECT sensors OE ?

I would replace the thermostat, again use an OE thermostat.

Also, only use Dexcool to replace the coolant.

 

[Bvogt]

Stuck open thermostat jumps out to me

 

[Trent_]

Well 1.8L engines are not my thing, but the 1.4L really need OEM sensors or they go nuts. Were the replacement ECT sensors OE ?

I would replace the thermostat, again use an OE thermostat.

Also, only use Dexcool to replace the coolant.

Thank you for the reply! They are ACDelco replacements. While I was not intending to I did get the Dexcool since it was on sale. Do you have any recommendations on where to source OEM components?

 

[Trent_]

Stuck open thermostat jumps out to me

Thank you for the reply! I was hoping it would be the sensors as those are cheaper but unless the third-party sensors are bad I agree that it may be the thermostat. Is there a way that you know of to test the thermostat to see if it is the issue before replacing it?

 

[Johnny B]

Do you have any recommendations on where to source OEM components?

Rockauto.com

 

[Bvogt]

Thank you for the reply! I was hoping it would be the sensors as those are cheaper but unless the third-party sensors are bad I agree that it may be the thermostat. Is there a way that you know of to test the thermostat to see if it is the issue before replacing it?

I’ve never tried to test one to be honest. Based on the temperature readings (if they are correct) it points to the thermostat being stuck open and not allowing the coolant to warm. I’ve just always replaced them. Rock auto and partsgeek have good prices on oem parts.

I recommend only using oem replacements only. Aftermarket may be cheaper, but when they fail, you end up having to remove it and replace with an aftermarket anyway. Keep us posted with what works and what didnt. Thermostat (don’t quote me) may be returnable where sensors cannot. Food for thought

 

[Trent_]

Looks like it was the thermostat. Finally got some time to replace it and I no longer have the issue of the coolant not wanting to heat up or cool back down once I get on the highway. Since replacing it I haven't gotten a P0128 code or seen the coolant temp needle go back to cool after the engine has warmed up. I also replaced the vapor purge canister valve which fixed the issue of not wanting to start after getting gas. Finally, my fuel mileage seems to be doing better now that the engine isn't running cool all the time. Thanks to Jonny B and Bvogt for your suggestions, I am very happy to finally have this issue solved.