# P0128 & P20E4



## Wendekay (May 20, 2018)

2014 2.0 td Cruze. 99000 miles. I’ve been clearing P0128 for a month or so, now P20E4 is coming up. I just have a code reader that I’m able to read and clear, nothing fancy. I can’t work on myself but I have a construction job with a great shop with lifts and guys that will help me change sensors and whatever that isn’t too crazy. Hoping someone can steer me in right direction as I’ve been trying to read some of the posts and I’m getting confused, might not be correct word lol. Help?? Pretty please?  really can’t afford and don’t want to take to my dealer.


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## Maqcro1 (Apr 29, 2019)

Wendekay said:


> 2014 2.0 td Cruze. 99000 miles. I’ve been clearing P0128 for a month or so, now P20E4 is coming up. I just have a code reader that I’m able to read and clear, nothing fancy. I can’t work on myself but I have a construction job with a great shop with lifts and guys that will help me change sensors and whatever that isn’t too crazy. Hoping someone can steer me in right direction as I’ve been trying to read some of the posts and I’m getting confused, might not be correct word lol. Help?? Pretty please?  really can’t afford and don’t want to take to my dealer.


probably a bad EGT sensor. They do go bad over time. Also I believe you have 3 of them. I’m sure someone with a diesel cruze can confirm this.


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## revjpeterson (Oct 2, 2013)

The P20E4 would be an Exhaust Gas Temperature sensor. You could find out if it was EGT2 or EGT3 by using a scan tool or bluetooth connector/app to view the EGT data and replace the one that's reading maxed out high or low. If you don't have a means to watch the live data from the sensors, they're only a $40-50 part, so you could just throw both sensors at it and call it good. 

The P0128 is a new one that I haven't seen before in the Cruze. Best guesses would be a thermostat that is stuck open or a Coolant Temperature Sensor that has gone bad. Getting the live data from the coolant temperature sensor would help narrow that down. Pegged out high/low would be a bad sensor. A temperature that fluctuates naturally, but never reaches operating temp, would be a stuck thermostat.


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## Wendekay (May 20, 2018)

revjpeterson said:


> The P20E4 would be an Exhaust Gas Temperature sensor. You could find out if it was EGT2 or EGT3 by using a scan tool or bluetooth connector/app to view the EGT data and replace the one that's reading maxed out high or low. If you don't have a means to watch the live data from the sensors, they're only a $40-50 part, so you could just throw both sensors at it and call it good.
> 
> The P0128 is a new one that I haven't seen before in the Cruze. Best guesses would be a thermostat that is stuck open or a Coolant Temperature Sensor that has gone bad. Getting the live data from the coolant temperature sensor would help narrow that down. Pegged out high/low would be a bad sensor. A temperature that fluctuates naturally, but never reaches operating temp, would be a stuck thermostat.


Thank you! It is running cool and will eventually warm up but cools down again. Do you know how difficult replacing a thermostat and/or would be?


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## revjpeterson (Oct 2, 2013)

Wendekay said:


> Thank you! It is running cool and will eventually warm up but cools down again. Do you know how difficult replacing a thermostat and/or would be?


In theory, it looks like you should be able to just unmount and push aside the ECM, then come at it from the left (driver's) side of the engine. Worst case scenario, you might have to get the charge pipe out of the way also, especially if you do the housing and hose along with it. I've never had to change mine, so don't know what other complications might arise in real life, though.


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## Blasirl (Mar 31, 2015)

Wendekay said:


> 2014 2.0 td Cruze. 99000 miles. I’ve been clearing P0128 for a month or so, now P20E4 is coming up. I just have a code reader that I’m able to read and clear, nothing fancy. I can’t work on myself but I have a construction job with a great shop with lifts and guys that will help me change sensors and whatever that isn’t too crazy. Hoping someone can steer me in right direction as I’ve been trying to read some of the posts and I’m getting confused, might not be correct word lol. Help?? Pretty please?  really can’t afford and don’t want to take to my dealer.


A code *P0128* may mean that one or more of the following has happened: 

Low engine coolant level 
Leaking or stuck open thermostat (likely) 
Faulty cooling fan (running too much) 
Faulty coolant temperature (ECT) sensor 
Faulty intake air temperature (IAT) sensor
Read more at: P0128 Coolant Temperature Below Thermostat Regulating Temperature


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## Snipesy (Dec 7, 2015)

Maqcro1 said:


> probably a bad EGT sensor. They do go bad over time. Also I believe you have 3 of them. I’m sure someone with a diesel cruze can confirm this.


5… Technically.
2 of them are EGR Temp sensors but they work exactly like the 3 other EGT sensors.


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## Wendekay (May 20, 2018)

Blasirl said:


> A code *P0128* may mean that one or more of the following has happened:
> 
> Low engine coolant level
> Leaking or stuck open thermostat (likely)
> ...


Wow!! Thanks so much for the info! I ❤ Y’all!


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