P0128

Hey TW just got a P0128 code on my code reader. Not too sure where the temperature sensor is. Do yall have any pictures? and have yall changed one before? i warmed up my engine and i see no leaks and the radiator is hot. Thanks TW

 

Just a caveat, I had this code on my old GMC. The temp sensor was easy to replace, but it wasn't the issue. I ended up needing to replace the thermostat after one of the rubber O-rings caused it to get stuck open.

Here's a video that may help though:

 

thanks bro!!!!! is it okay to drive with a P0128?

 

Yeah. I believe they're designed to fail in the open position. But your engine likely will never get up to the proper temp.

 

yeah ima just wing it for a lil bit gonna buy the sensor tomorrow or something. thank god its not as bad as i thought. tacomas are beasty

 

is the placement on the sensor differ from tacoma engines? im a 2rz. is it the same as the video shown above?

 

and also could it be a thermostat as well?

 

Sensors are cheap, which is nice. Always start with the cheap things first. Watch your temp gauge next trip. See if it raises at all. Mine rose, but stopped short of normal and then the code threw and showed no temp. If it's not reading a temp at all, I'd say it's most likely a sensor, but if it slowly rises like I just described, may be time for a new thermostat.

This is for the 2.7:

 

Wish the video was longer thanks though bro! Ima try to look for it

 

Found it its like in the back of the engine looks like a bitch to get too lol

 

Yeah it was easy to change for me, but definitely a pain to get to.

Also, if you hit "quote" to respond, I'll get a notification that you did.

 

Why don't you test things first before throwing parts at it? What does your code reader say the coolant temperature is once the engine is running for a while? I'm saying maybe the thermostat is bad and throwing a cheap sensor in might be worse than keeping the original if it still works. The best thing to do is go through the diagnostic for P0128 in the Toyota Repair Manual to see what could cause the code.

 

Check your wiring. I have repaired a few first gen with melted/ broken/ chewed through wiring that was touching, causing the code before you replace the sensor. Make sure the wiring isn't faulty. It's right in front of your face more on the passenger side on the engine as soon as you pop your hood.

 

Yeah im going to try and test it out tomorrow and warm up the truck. How long tho? And what if the temperature gauge doesnt rise to the middle from c and h? And i think my sensor is in the back of the engine block..

 

Ill look for wiring too

 

How do i decipher if its the thermostat or the sensor?

 

The gauge uses a different sensor than the ECU uses to measure coolant temperature (unless something changed in later Tacomas), so it's best to look at the OBD reading that the ECU reports. It should steadily rise and reach at least 180°F.

You can test the resistance of the sensor and compare it to a chart. You probe the 2 terminals with a multimeter set to ohms. The resistance varies with temperature and this is how the ECU determines the coolant temperature. The ECU just translates this to the OBD live data, so it's easiest to just look at this first. If it's reporting -20°F then you know something is wrong with the sensor or wiring and you can check those. If it seems to report what you'd expect, current outside temperature when you first start and steadily rising but never getting above 140°F, then you'd be more likely to suspect a stuck open thermostat.

 

Just be sure to update us no matter what happens

 

Wow! Thanks for the info guys!!! I will test it tomorrow! I will keep you posted thanks so much!

 

Hey guys so i warmed up my car for about 15 mins and did like 10 mins of driving and i hooked up the obd scanner and this what i got