'coolant sensor bad' message flahses on lcd panel.

It is possible that you have an airlock in the coolant system? That can cause symptoms of overheating and sometimes there isn't sufficient flow or the coolant temperature. The main tip is to turn the heater of full heat and also elevate the front of the vehicle.

https://www.fixya.com/cars/r29872074-vehicle_cooling_system_no_heat

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Trace the upper radiator hose toward the Grand Cherokee's engine until you reach the metal component connecting the hose to the engine -- this is the thermostat housing. Find the coolant temperature sensor -- the electrical component on the thermostat housing. Press the locking button on the coolant temperature sensor wiring harness and pull the wiring harness from the sensor, then remove sensor it screws out. when putting in new sensor coat the threads with teflon pipe thread tape so there is no leaks.

Hello: You didn't post what year/model car. If its 1996 or newer the coolant level sensor is located in the overflow tank. Sometimes you can tap on the tank near the sensor and it will work. Make sure the sensor is connected, not easy to get access to it. To replace the sensor you will have to replace the tank.

have you checked the plug in at the coolant resevoir? if good, have you checked the fuse panel for blown fuses? low coolant light comes on because the sensor n the coolant resevoir tells the computer says there is not enough fluid in your resevior, the clear tank under the hood that connects to the radiator. you may have a bad plug in or a bad resevoir. i suggest you check fluid,,if good ,,check plug in,, if good,,replace resevoir,, hope this helps!!

Coolant Sensor send bad signal to the ECU and the engine is work with abnormal parameters. Unplug the coolant sensor and clean the pin harness, sometimes this work, If not fix the problem, you need replace this sensor. For other details about Cooling System check your Service Manual ZJ-Secc-7-Cooling-System

Hope helps (remember rated this) Good luck.

The coolant sensor and the coolant level sensor are two different sensors. Your message center is showing (coolant sensor bad),not level sensor bad.
The level sensor only monitors the amount of coolant in the container
The coolant sensor senses the degrees of the coolant, which turns on the electric cooling fans. Change the coolant sensor, and the problem should go away.

Your VIC doesn't provide you with codes per se, it supplies other information and what you describe here is what should be written on your VIC, "Coolant Sensor Bad." The actual Coolant Sensor runs to your PCM or computer and your check engine light will come on if it runs at or above 5 volts or below 0.1 volts. If the red square on the vehicle layout is illuminated under the hood area, it means that your Coolant Recovery jug is either low on anti-freeze or the sensor next to the yellow filler cap is faulty...meaning you're low on Coolant and the VIC says that the "Coolant Sensors Bad" yet it's the amount of fluid in the plastic bottle next to the passenger side firewall, right in front of your PCM or computer. If you're low on anti-freeze, keep an eye on it, or have the coolant system pressure tested...including the 18 pound cap on the radiator itself. Also check the two wires hooked to the Coolant LEVEL Sensor in the jug with an Ohmmeter and it should be an open circuit if the level is fine, or hardly any Resistance if the level is low, causing that circuit to complete it's ground circuit and thus signaling the VIC through your BCM to turn on. (Body Control Module). The Haynes Manual you will need is # 50025 which encompasses all Jeep Grand Cherokee's from 1993 thru 2004.

~Stillin~

This problem is frecuently in this models, check the levels, check and clean the plug connections and Reset your ECU.

Also, can reviewthe #8 wire in a ribbon connector, the factory that made the VIC's use awave soldering method, and the #8 pin (which is the coolant sensorground pin -IIRC it's pink- will have a cold solder joint.

If you cansee faults in this connections, it takes about 15 minutes to get the VICout of the car, and if you cansolder, another 5 to fix the problem. I'dadvise re-soldering all the connections, while you're in there.

If the problem stay there, just change your coolant sensor.

Good luck, and remember rated this help.

The Coolant Sensor is inside coolant bottle; in this models is common ths message failed; clean the plug and reset your ECU alarms, if the message come on again, replace your coolant sensor. And, really, one message about a bad sensor/signal is one bad work engine.

Good luck.

Check the plug conector from the coolant sensor at the ECU, maybe cleaning with dielectric solvent you will can have a solution.

Review this doc Secc-7-Cooling-System / Page 7-23 ...

Good luck