[Jerome_Arlington]

Yesterday morning, I notice that i did not have the usual temp display when I arrived at work. Same thing on the way back + in the middle of the trip the Check Engine Light came on.

Checked with OBD, and it gave me the P0128 message.

Hot air is blowing so I am assuming I have proper water flow (I'll check tonight radiator temp).

Does the Engine Coolant Temperature sensor seem a logical explanation from here?

 

[Mr.C]

Not sure if this helps but here is an explanation of P0128 with possible causes (with compliments form the internet)

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

 

[Jerome_Arlington]

Well, I decided to start by the temp sensor.

Apparently alternate Toyota Ref is 89422-35010.
(Found it 2 minutes after placing PO for the Lotus ref A120E6375S).

 

[Jerome_Arlington]

Well.... The Toyota part number ended up being more expensive than the lotus one...
That was a surprise.

 

[Westrock]

This sensor is just the one that screws into the block?

EDIT: Looked up the part number, ya just the little sensor.

 

[Jerome_Arlington]

Correct, it was this sensor.

Turn out to be the other option: Stuck open thermostat.
Right on the 24k mark.

Replaced, and now proper temp regulation.
I was missing the 8000 rpm sound of this engine.

Thank you Y'all

 

[Rainier]

I got a check engine light today and the following codes were listed.
Im not sure if some of these are old codes, they are listed in order.

1. P0507 Idle control System Idle Higher than Expected

2. P0481 Cooling Fan 2 Control Circuit Malfunction

3. P0646 A/C Clutch Relay Control Circuit Low

4. P0480 Cooling Fan 1 Control Circuit Malfunction

5. P0128 Coolant Thermostat (Coolant temperature Below Thermostat regulating Temperature)

Only noticable symptom is that the temperature display can rapidly drop from normal when getting on the second cam under hard acceleration, the display then quickly comes back to normal temperature when cruising.
<edit> Should mention this syptom first started after having both the oil coolers replaced as part of the oil line recall back in November..didnt think much of the issue at the time and today is first time getting a check engine light<edit>

Any ideas? Possibly loose wire? Replace the thermostat?

Thanks in advance for any advice.

 

[sturgeongeneral]

It sounds like they swapped the fan leads.