Code P261B while driving in the highway

I think it's a few minute job to pull the water pump off and then before I disassemble it hook up the software call up the water pump see what the impeller looks like when it tries to spin or does spin then if it does not spin satisfactorily or extremely slow pull it apart and see the plastic rotor and impeller damage and then go from there.

 

Also do a quick check of your electric cooling fans. Turn on your AC, set the temp to low and make sure both cooling fans are turning. If one or both fans aren't turning - you can disconnect the power wires and jump them directly to a battery to determine fan or control issue.

Hope this helps...

PS. if that car has that electronic diverter valve, look at that too. It may not be sending coolant to the radiator.

 

I have the generation too that's doing this right now but it does not have that code and it doesn't have an electric water pump and it is all working properly but the temperature still spikes there there's a small leak somewhere that I have to find a drip actually and even when the car's down say a mason jar full of coolant low when I'm getting on it on the highway the red triangle will come on and I'm positive it's telling me that my temperature is getting high and then it immediately goes off then it comes back on every few seconds what have you then goes off then comes back on so I'm not sure maybe the thermostat might be sticking possibly or the sensor might be going bad because the car doesn't really feel hot and it's not missing or acting up.

 

I suspect the area of the highway your talking about is a slight up hill requiring more power from your ICE. Your water pump isn't ramping up to keep up with the increased power demand. As soon as you crest the hill and back off the accelerator; the engine will begin to cool down. Bottom line, sounds like a borderline water pump issue. You wouldn't see this issue in the winter time under cooler weather, but as we get into the scorching summer - your issues will increase.

 

I would change the entire assembly rather than split hairs between rotor and pump. The ECU ramp up signal isn't likely to be an issue, unless you've got rodents chewing on you wiring harness or your harness is rubbing body panels creating a short. That would cause temperature spikes and drop outs..