crownjewel
Member
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- Mazda 5
I just thought I'd share this because I found conflicting information out there and a few dropped threads. My vehicle: 2009 Mazda 5 Sport (5 Speed Auto) with 122K miles. A few weeks ago while accelerating on the street I experienced hesitation in the transmission, then the AT light turned on for a second then turned off, then a CEL. The transmission shifted normally after that, the speedometer worked fine, and everything continued to work as usual. The CEL read as P0720 Output Shaft Sensor Circuit. I used the code reader to clear the code, but within a few days I experienced the same thing and CEL turned on again with the same code. Despite the dealer diagrams it was confusing to tell exactly where the the sensor nearest the output shaft was.
From my research, I found that the Mazda 3 and Mazda 5 with 5 Speed Auto Transmissions have a total of 3 speed sensors:
One FN0121550 (located underneath the intake airbox), and two FN1221551A (one is located under the battery, the other is located under the car, towards the back of the transmission. To make matters more confusing, Mazda does not label their sensors with their corresponding use, example: Generator Pulse Sensor and Turbine Speed Sensor.
I first replaced FN0121550 under the intake air box, but the car threw CEL P0720 once again. I then replaced FN1221551A located under the battery, but the car registered the same P0720 again within 2 days. The final fix was replacing the second FN1221551A located under the car, rear of the transmission and NEAR THE OUTPUT SHAFT. The output shaft is clear as day once you're underneath the car.
Anyway, I hope this helps someone. All sensors were OEM purchased from Mazda, each was between $90-$100 retail. Aftermarket versions can be found for about half.
Edited 9/5/17
After one week of replacing all three speed sensors with brand new OEM units as explained above, the car once again threw P0720 CEL. The last ditch effort before taking the car to a dealer was to replace the Transmission Control Module (TCM) myself. The TCM is much more expensive (near $500.00) than the speed sensors, but easy to do so I gave it a shot. It's located underneath the battery. Once the battery and battery tray are removed, you'll need to remove a black bracket that has a weight on one end. It's held on with two bolts (17mm, I believe). The TCM itself is held on with three 10mm bolts, and they are not the easiest to get to. You'll also need to some pliers to squeeze and remove a wire loom fixture attached to the top of one of those 10mm fasteners. My old TCM was part# L39C189E1C. My new unit was brand new OEM purchased from the dealer (verified correct replacement part# with my VIN#), new part number is L39C189E1E. It's been over 1 week since this has been installed and no more problems. I'll edit once again if any other problems occur.
Edited 10/3/22
TCM had not been relocated and is still in the original location, just maintaining regular transmission fluid changes since the original date of my post, and the transmission is still working great.
From my research, I found that the Mazda 3 and Mazda 5 with 5 Speed Auto Transmissions have a total of 3 speed sensors:
One FN0121550 (located underneath the intake airbox), and two FN1221551A (one is located under the battery, the other is located under the car, towards the back of the transmission. To make matters more confusing, Mazda does not label their sensors with their corresponding use, example: Generator Pulse Sensor and Turbine Speed Sensor.
I first replaced FN0121550 under the intake air box, but the car threw CEL P0720 once again. I then replaced FN1221551A located under the battery, but the car registered the same P0720 again within 2 days. The final fix was replacing the second FN1221551A located under the car, rear of the transmission and NEAR THE OUTPUT SHAFT. The output shaft is clear as day once you're underneath the car.
Anyway, I hope this helps someone. All sensors were OEM purchased from Mazda, each was between $90-$100 retail. Aftermarket versions can be found for about half.
Edited 9/5/17
After one week of replacing all three speed sensors with brand new OEM units as explained above, the car once again threw P0720 CEL. The last ditch effort before taking the car to a dealer was to replace the Transmission Control Module (TCM) myself. The TCM is much more expensive (near $500.00) than the speed sensors, but easy to do so I gave it a shot. It's located underneath the battery. Once the battery and battery tray are removed, you'll need to remove a black bracket that has a weight on one end. It's held on with two bolts (17mm, I believe). The TCM itself is held on with three 10mm bolts, and they are not the easiest to get to. You'll also need to some pliers to squeeze and remove a wire loom fixture attached to the top of one of those 10mm fasteners. My old TCM was part# L39C189E1C. My new unit was brand new OEM purchased from the dealer (verified correct replacement part# with my VIN#), new part number is L39C189E1E. It's been over 1 week since this has been installed and no more problems. I'll edit once again if any other problems occur.
Edited 10/3/22
TCM had not been relocated and is still in the original location, just maintaining regular transmission fluid changes since the original date of my post, and the transmission is still working great.
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