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post #1 of 19 (permalink) Old 10-08-2015, 07:24 AM Thread Starter
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P0128 Keeps Popping Up

For the second time in less than a week now I got a cel for a p0128, when it comes on the temp readout on the dash just displays "---" and the fans kick on high and stay on. I have my aero force interceptor gauge plugged in and monitoring the coolant temp and it works perfectly fine and seems like the temp is normal even when the code pops up. If I clear the code, everything instantly goes back to normal like there was never even a problem and it is frustrating!
Really want to get this figured out before I put the supercharger on this weekend, anybody have any idea what is going on?

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post #2 of 19 (permalink) Old 10-08-2015, 07:33 AM
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Well, it looks like you already know what the code means, but just for future reference:

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P0128 Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature
Maybe a bad sensor? Is your aero force attached to the stock sensor?


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post #3 of 19 (permalink) Old 10-08-2015, 07:35 AM Thread Starter
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Well it just pulls the data from the obd2 port so yes, that's why I'm so confused by this.. this morning it popped up after 3 miles and the temp was at 183 when it happened..

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post #4 of 19 (permalink) Old 10-08-2015, 07:39 AM
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Hmm, well that's weird. 183 seems pretty normal to me. Do you have enough coolant in the car? Low coolant levels sometimes cause that code.

OBD-II Trouble Code: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)


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post #5 of 19 (permalink) Old 10-08-2015, 07:43 AM Thread Starter
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Coolant level is still exactly where it should be, that's the first thing I checked the other night

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post #6 of 19 (permalink) Old 10-08-2015, 07:57 AM
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I assume you've also made sure it doesn't need to be changed, right?

Looks like a faulty air intake temp sensor can cause it. I assume our MAF has one of those, but I honestly don't know.


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Last edited by Parthros; 10-08-2015 at 07:59 AM.
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post #7 of 19 (permalink) Old 10-08-2015, 08:02 AM Thread Starter
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IAT seems perfectly normal as well, that's the other thing I have the interceptor displaying haha, and the coolant? It's still good, it was changed shortly before I got it but I planned on flushing it out in the springtime

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post #8 of 19 (permalink) Old 10-08-2015, 08:07 AM
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Hmm, well that definitely makes it puzzling. I'm all out of ideas... and so is Google, haha

Maybe you'll find something after you log all the data on your laptop!


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post #9 of 19 (permalink) Old 10-08-2015, 08:15 AM Thread Starter
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I hope so haha, short of that I think I might just go ahead and replace the thermostat and the sensor...

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post #10 of 19 (permalink) Old 10-08-2015, 08:51 AM
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The rubber gasket probably folded over and is letting coolant by not letting temperature come up fast enough. You just need a thermostat.

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