AT and Check Engine Light On
 

Would like to share my experience here. I have this problem with my Mazda 2 SP (2006) gear box. AT and CEL turns on while driving and will shift from gear 4 to 3, when i put my vehicle to a full stop the AT light goes off but CEL remains. Went to several workshops and all suggest either to change a recon gear box or to do a gear box overhaul. , which cost ~SGD$2500. However whenever they do a scan for error code, it points to 'Turbine Speed Sensor Circuit Fault'. I called Mazda to ask about this turbine speed sensor and they informed that it actually not a major issue. Got one of the workshop to have it replaced (did not go to Mazda as they need to do a diagnostic which cost SGD$190 before they do any replacement). Have to say that it is really simple to replace, the speed sensor is just located to the right side of the gearbox near to the battery. Just removed the battery and will be able to reach it from the side. There is a connector and bolt that u need to lossen before u can remove it (google it and u will be able to find out more about removing, that is if you plan to remove it yourself). End of the day it cost me SGD$180 include labour. Word of advice is most of the workshop will tell you that the speed sensor is located IN the gear box and require an overhaul to have it replace, or that some lost of pressure is causing the error, please don't be tricked by them, they are just trying to ripped you off your cash. So far my car is running fine with no more error.