CHECK ENGINE ON

This seems a bit odd to me. The coolant temp sensor sends a signal to the engine control module, the engine control module tells the instrument cluster where to position the temp needle. So, if the engine control module thinks the temp is too low, I would expect the temp to read low on the dash gauge. But I don't know how low it needs to be to trip the code. It's probably only a 10 or 15 degree difference from normal, and that may not be visible on the gauge.

I still would start with the thermostat.

 

BECK/ARNLEY Part # 1430714 Thermostat TEMPERATURE 180 $10.86


STANDARD MOTOR PRODUCTS Part # TX109 Temperature Sender / Sensor $39.79

 

Factor in the cost of your time and it may make sense to swap them both out, that way you only drain and fill the coolant once. Might be a good opportunity to change the coolant too. I'm cheap, so I would start with the thermostat and hope to save the bucks on the sensor.

 

Thats alright price i thought the sensor was gunna be way more expensive. Start with the thermostat then the sensor

 

Is there any write uo on how to change the thermostat or the sensor?

 

I'll see if I can find anything

 

Code p0128 - Engine coolant temp does not reach 158Deg F despite sufficient engine warm up time. This is a thermostat regulating code.

The ECM estimates the ECT based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual ECT reading. If the actual ECT is less than 158 Deg F, the ECM interprets this as a malfunction in the thermostat or the engine cooling system, and sets the DTC.

Check the cooling system for defects that may cause the system to be too cold, such as abnormal fan operation or any modifications. Thermostat should open between 176 to 183 Deg F. A stuck open thermostat will not allow the engine to warm up quickly. Most common failure in this code is a thermostat, however a bad ECT sensor can also cause this. Since you have found them both to be inexpensive, replacement of both would not be too difficult. If I had to choose though, I would do the thermostat first.

 

Could it be the aftermarket fan? I didn't considered it because it has been installed for 4 months ans haven't had any issue. It's the

$572 Flex-a-lite 678 S-blade Engine Cooling Fan with Controls for Toyota Tacoma 05-09 , Black

Flex-a-lite 678 S-blade Engine Cooling Fan, I replaced the clutch one for this one.

 

There's a reason he only makes $8.50/hour, and there's a reason that he is violating state law if he does anything more than allow you to read codes.
He can not legally interpret the codes.
This is one of the reasons why that law was passed a few years ago.


It is likely one of two things.... your thermostat is stuck open, or your temp sensor is bad.
It could also be that the connector to the sensor is unplugged. Check the connections before buying any parts. What was the last thing you did under the hood?

Temp sensors work approx 5 years? He is completely full of shit.

 

Is it illegal for them to interpret codes?
I think the sensor isn't unplugged because the gauge in the console works like always, starts from cold and like in 2-3min with the engine running gets to the middle.
The last thing I did to my truck was installing new terminals and a blue seas fuse box.
So whats the approx life of temp sensors?

 

^ Everyone here needs you on speed dial.

 

It is illegal (California law) for him to do anything more than look up specific parts that you request and sell them to you.
He is not a tech. He has had no formal training as a part of his job. He may have attended some sales seminars.
It is illegal for him to connect the code reader to your vehicle.
This was all pushed through by the ASE lobby.
Unless a business has an actual service department, they can not legally troubleshoot your problem.

It is likely against company policy for him to physically touch your vehicle, most will look the other way for things like wiper blades.

There may be more than one sensor.... but I'd follow Bama's recommendations. He's more familiar with the Tacoma under the hood than I am.

Decades.

I've never had one go out.

 

This^^^^ I also have never had a coolant sensor go bad and I'm an old bastard by a lot of you guys standards (57).

I agree the thermostat is most likely stuck open.

There is one other thing I have seen before. A low coolant level in the engine block in which the sensor is not immersed in the coolant will cause it to read a low temperature.

 

Judging from Bamatoy's description of what that code means, I'd say there's a possibility that your fan might be the culprit.

Basically, the engine isn't as warmed up as the computer thinks it should be after a given period of time under certain conditions. It doesn't know you've got the aftermarket fan. It may be that the fan is keeping things cooler under the hood and preventing the engine from warming up fast enough to satisfy the computer.

Put the stocker back on and pull the negative battery cable to clear the code. If it works, it's a free repair.

Edit: I googled that fan, looks like there is an adjustable thermostat for the fan? If so, set it to come on at a slightly warmer temp. That might be enough to get the engine to warm up faster.

 

Most codes will clear themselves after a few restarts once the fault clears.

Whether the fault clears, or the battery is pulled, it still needs 15-30 restart cycles before the buffers are full for a clear smog check, and pulling the battery resets the fuel and idle trims.

I do everything I can to avoid pulling the battery completely... including connecting an old motorcycle battery to the terminals before changing one.

 

I recently left the gas cap loose on my work truck. The CEL came on and stayed on after I tightened the cap. I thought it might reset since it was likely an evap system code. It did not. Pulled the cable, the light went out. It's been several weeks now and the light is still off. No ill effects that I noticed. It's an 09 2.7 Tacoma. I suppose if he's got a smog check next week it might be a consideration, but it's not going to pass with that light on anyway.

My Chrysler corp vehicles were another story. The old Dakota used to require me to drive with all three of my feet to keep it idling for the first few miles after a "reboot".

 

Each code has a parameter based on what type of code it is as to how long it will take to reset. Some codes will reset after a single restart, others must wait for the system to perform a certain number of "code pest passed" before the light will be turned off. The "gas cap" code (p0446) is one code that is a bitch to reset itself, so most people clear the code, or disconnect the battery.

To properly pass emissions testing, the most challenging code is the p0446. The reason this is such a challenge is because the pass for this code takes up to 4 or 5 cold start cycles to perform.

As for a fan issue, you will very rarely have a fan to cause this code to set. The reason being that if your thermostat is properly closed when warming up the first time, then airflow across the radiator won't have any affect on engine coolant temperature. However if the thermostat is stuck open, even a small amount, then the engine will not warm up as expected. Do take notice that a thermostat does not shut off all flow. There is a metered bypass hole that allows a minute amount of water to bypass it. This allows for easier refilling, and to prevent air pockets.