My friend was using my car (with my permission) and drove to Houston from Austin. The check engine light came on and she called me from a service station. The gentleman suggested she remove the left cable from the battery and then replace it again. I told her it has never come on before, try the gas cap and radiator cap to be sure they are on correctly and tight. The service station said they charge 100.00 to use the Diagnostic Car Reader. She decided to leave and while backing up the attendant asked her to stop, get out and look at the ground under the car. There was coolant. She decided to leave it with him to have him check it out and she left. He did attach the Reader and said the code was about the water pump. He said Mazda had a special tool to remove it and he didn't have that tool. He also looked up the labor time involved and said even though part under 100.00 the labor was several hours. She ended up driving it back to Austin and the Check Engine light is still on. There is nothing leaking out of the car and the coolant is still at the same full levels and the car never over heated. This is a 2011 CX9 Touring with 102,500 miles. Great condition no problems and just had front brake pads and rotors replaced. Have never had any major issues with it and oil changes are regular too. Any ideas out there?

 

Ok so I just drove it two blocks and and do see that it is leaking coolant. It leaks on the same side the A/C condenser would expel water. The A/C not on. I touched it and it is greasy and dark and smells like coolant. Not green like coolant but it's more black. The reservoir is full if not over full but it isn't coming out the overflow tube at all. Perhaps the water pump is failing and no coolant is leaving the reservoir at all?

 

Not familiar with your car but that has never stopped me from butting in before :-) So, does your car have a temperature gauge? If so, does that gauge measure the temp of your coolant or oil or? If you are leaking engine coolant, sooner or later your engine will get over temp which is not a good situation. So if your gauge is coolant, keep a very close eye on it and if it goes over temp, shut off the engine right then and there. I would go down to your local auto parts store, most will be happy to connect their OBD reader and tell you what the codes are, for free? They hope that once you find out what part you need, you will buy it from them. If you do your own work, they also loan out tools. Maybe they will tell you what the code means or you can search for it on the internet. If you have a friend who has a code reader, that would be good so you don't have to keep driving the car not knowing what's wrong.

If the check engine light is on, there should be at least one code in the puter. Also, if you are close to a state inspection, most inspection stations will not inspect it if the check engine light is on, just be aware of that. You said the fluid is black or black-ish and oily? Not good in that it could be a blown head gasket in which coolant is mixing in with the engine oil. When the engine is cold, open the coolant expansion reservoir cap and look inside and see if what you see matches what you found on the ground. You may have to dip a white paper towel into the fluid to get a better idea of what it is.

You might do well to put a clean white towel or a number of plain white paper towels under the area of the car where you see it leaking and then see how much leaks after a spin around the corner and what the color and feel is like. Combine all that you see and feel with the codes from the OBD scan and you may then have a better idea of what you're dealing with.