Code P0125

obd-2 code P0125 is the code that came up on my 99 Mazda 626 but before the check engine light came on my cars temperature gauge would go to hot when sitting in traffic but when I am driving and accelerating it goes right back to normal temperature. we have checked the coolant level and it is fine. do you have any suggestions of what I should consider doing next? please help! THANKS, CONNIE

Steve Says,

Thanks for asking me your code question. It sounds like your main problem is a cooling system problem. The first thing to check is your cooling fan. Right before it starts overheating you need to pop your hood and see if the cooling fan is coming on. If it is not then that is probably the problem. If it is then you might have a faulty thermostat or even a bad head gasket.

Most likely the overheating has caused the coolant temperature sensor (cts) to go bad. It is possible that your whole problem is caused by a faulty coolant sensor. If it is bad it could be giving you faulty temperature readings and causing this code as well. If you want to check it just get a thermometer and put it on the thermostat housing and see how hot the engine gets. See if it gets as hot as the gauge says it does.

I hope this helps.