Welcome to JustAnswer.com! My name is DriveFast71(Ron) and I will do my best to answer all of your questions completely and accurately.
Do you happen to have the actual "p-code" associated with this?
How did you come up with the dioagnosis of "weak coolant"?
And the actual description said "weak coolant" and there were no "p-codes"?
That'd actually help us out a TON. With the p-code I can help you diagnose the actual problem more accurately.
No prob. Just reply back to this thread like you have been, and we'll pick it up right from here.
The code is P-0126 and it says "insufficiant coolant temp for stable operation"
Ok. There are a couple of things that can set a P0126- either a faulty Engine Coolant Temp (ECT) Sensor or a faulty Thermostat. To test the ECT you will need to have an Ohms meter and a thermometer. Remove the ECT and set it into water or varying temperatures, and take resistance readings. If the ECT passes the tests, replace the Thermostat.