Cold engine light randomly comes on while warm.

[gboezio]

Am I the only one who gets the cold light to come on while driving ??
When I mean driving, I mean on the highway for 30 minutes.

I have searched the forum for this and it does not seem to be a common problem. The heater is blowing hot air at will, the coolant level is right on, I figured that maybe the ECT sensor is faulty, but the ECM throws no codes and should, unless there was air or steam pockets in the coolant stream or the engine temp dipped under 130 F ??

Unlikely I say, but any input on this will be appreciated.

Anyone knows the resistance of the ECT @ X temp in ohms ?

[faridmakhloufi]

my same problem i have a toyota yaris 1.3 engine 2nz-fe with 150000 miles but this appears only in winter or cold weather please help me

[tmontague]

Could be a faulty water temp sensor. Even when my car goes back below 129 degrees F the sensor doesnt kick back on, so once it's off it should stay off even if the cars cools down due to running the heat.

Use a scanner to read coolant temp and see if your sensor is shot

[ex-x-fire]

Yeah, could have a t-stat that won't close all the way. Best way is to scan it. Let the car idle till it gets to 180 or 190. Drive it, the temp shouldn't fall below 170 or so.

[faridmakhloufi]

i have changed the ect sensor and the thermostat the problem is persisting and i have scanned the memory no error codes it is very strange realy i I think it's the maf that gives false data on the air temperature , not sure