My coolant light keeps going on. At first it was when I would drive on highway but would go away after it goes out of gear(neutral). Today it appeared again but it’s doing the opposite now it stays on when the car isn’t moving or on neutral. Any idea on what it can be?

 

A common occurrence. The float sensor goes out over time. That is what it is if you checked your coolant level and it is good. You can't just replace the float sensor, you have to replace the whole reservoir bottle with the sensor. Some here will tell you just to unplug the sensor and keep an eye on the coolant level, but you risk being late on a leakage that could cost you an overheated engine.

Best advice replace the bottle. MazMart is a good source. Be sure to order the bottle with the sensor.

http://shop.mazmart.com/en/rx8-coolant-bottle

 

Search "coolant light on dash". It's probably the most common issue ever.

 

Yes, replace the bottle. Note that this is/was a known problem, and the replacement bottle w/sensor listed above is Mazda’s REVISED design to eliminate this very problem.

 

Thanks. You guys recommend the priciest one?

 

All you need is a new coolant expansion tank from Mazda. It has the sensor built in as stated. Doesn't matter where you get it as long as its o.e. The priciest one isn't necessarily the best in this case as there is only one to choose from and it comes from Mazda.

 

http://shop.mazmart.com/en/rx8-coolant-bottle


Easy if you read the descriptions, just order the coolant bottle with the sensor. The price differences are simply because Mazmart has them with or without the sensor,and with and without the cap. Get the one with the sensor, simple ok. You can reuse your stock cap and save a few dollars.