DTC code P0720/ Engine light and AT light
#1
12-26-2018, 04:22 PM
DTC code P0720/ Engine light and AT light
I have a 2008 Mazda 3 hatchback with 89,700 miles. Approximately 2 months ago the engine light and AT light would intermittently come on, sometimes together, and sometimes only the engine light alone. I noticed the transmission slipping when shifting out of 3rd gear. (this is a semi-automatic transmission and I only drive it in automatic). I decided to use an OBD scanner which displayed P0720, I looked up the code and it indicated a problem with the output speed sensor. My mechanic changed the sensor and reset the code, 24 hours later the engine light and the AT light came on again. I also noticed that this typically only happens while accelerating into 4th or 5th gear and the transmission will not shift outside of 3rd gear despite acceleration in speed. I brought this up to my mechanic and he thinks I should have the Transmission Control Module changed because he's not sure what else it could be. I'm hesitant to have him change this for a few reasons:he doesn't seem confident that this is the problem (I've already put out $200 to change the sensor and this would be an additional $850 including parts/labor/programming), I'm wondering if I should take my car into a Mazda dealership to have a diagnostic test completed (would the dealer service department be able to pinpoint the problem?), I've looked this up and I feel confident that I can change the TCM myself if that is the issue but does it really need to be programmed? I've read a few forums stating that the TCM does not need to be programmed and some that say it does, hmmm?? Any advice on the issue would be greatly appreciated. This car has been great to me the last 10 years I'm hoping to keep it as long as I can.
#2
12-28-2018, 06:25 AM
There are two "speed sensors", quite often people replace the wrong one.
Mazda are the experts on your car, and have superior scan tools.
Mazda are the experts on your car, and have superior scan tools.
#3
12-28-2018, 03:55 PM
Thank you @grim_reaper , I did not know there were two speed sensor and I don't think my mechanic does either. I'll will take my car to Mazda.
#4
09-14-2021, 09:04 PM
I have a 2008 Mazda 3 hatchback with 89,700 miles. Approximately 2 months ago the engine light and AT light would intermittently come on, sometimes together, and sometimes only the engine light alone. I noticed the transmission slipping when shifting out of 3rd gear. (this is a semi-automatic transmission and I only drive it in automatic). I decided to use an OBD scanner which displayed P0720, I looked up the code and it indicated a problem with the output speed sensor. My mechanic changed the sensor and reset the code, 24 hours later the engine light and the AT light came on again. I also noticed that this typically only happens while accelerating into 4th or 5th gear and the transmission will not shift outside of 3rd gear despite acceleration in speed. I brought this up to my mechanic and he thinks I should have the Transmission Control Module changed because he's not sure what else it could be. I'm hesitant to have him change this for a few reasons:he doesn't seem confident that this is the problem (I've already put out $200 to change the sensor and this would be an additional $850 including parts/labor/programming), I'm wondering if I should take my car into a Mazda dealership to have a diagnostic test completed (would the dealer service department be able to pinpoint the problem?), I've looked this up and I feel confident that I can change the TCM myself if that is the issue but does it really need to be programmed? I've read a few forums stating that the TCM does not need to be programmed and some that say it does, hmmm?? Any advice on the issue would be greatly appreciated. This car has been great to me the last 10 years I'm hoping to keep it as long as I can.
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