At work right now and don't have them handy but as far as memory serves -

P0116 Engine Coolant Temperature Sensor Falling Temp Fault

Is all that is being shown now....

 

If I remember right a 116 is a performance temp issues usually indicating there is too much difference between your 2 temp sensors which can indicate you are still having some sort of a cooling issue and not a failure on the part of the sensor.

 

Wouldn't overheating drive both sensors up together? Or do you mean in terms of circulation?

 

0116 is ECT sensor out of range low temp. Like it is unplugged, or open. My scanner reads -40 when ECT unplugged. See pages 65 - 70 of attached GEMS manual. I believe the D2 behaves as Mike says, and uses two sensors to detect if thermostat is stuck open or other cooling problem. If ECT is unplugged, could make truck run rich.

The two sesnors on the D1 are single wire - analog guage, and two wire (ECT for ECU, also shows up on OBDII port). It is the one with square top in pix.

The ECT tells the ECU the temp. You can see in pix that ECU thinks it is 235F, and gauge thinks that is normal. Hogwash!

 

Are you saying that on a D1 that a broken sensor will cause both the temp guage to read high as well as send wrong temp to the ECU? This could explain the high temp showing on the guage as well as the OBD2 code getting thrown.

 

No. The one wire sensor sends data to the gauge. The 2 wire sensor sends data to the ECM. The ECM cannot control the gauge. But one of the sensors being bad can have bad results. The 2-wire being bad tells the engine false data and can ignore an overheating engine. The one wire sensor can give you peace of mind when you should be alarmed by an overheating engine.

 

Ok. Makes sense.

However, now the code is telling me my one sensor is not operating/reading cold and the other one is showing climbing temperatures despite driving the truck for almost 2 hrs with no issues after replacing the rad.

I just do not know what to think now.

 

Make sure the connectors are clean and pushed all the way onto the sensors. So from what you posted, the gauge is saying you are overheating but the ECM is saying your engine is not warming up. Is that correct? In that case, I'd trust the sensor that says you are overheating to be safe and replace the other. Or just replace them both. They don't cost much and are available at most parts stores.

 

Atlantic British lists the 2 sensors at $20 and $18.

 

From personal overheating and eagle eye watching of gauge..that position above center is t-r-o-u-b-l-e. while dead on center may be hot any movement above is danger zone...in my opinion.