Intermittent engine shutting off issue

Welcome to 2CarPros.

One of the most common issues is a bad crankshaft position sensor. Can you let me know if this happens when the engine is warmed up? Does it happen when the engine is cold?

If it only happens when the engine is hot, the sensor may be breaking down internally and losing connection due to expansion resulting from heat. Take a look through these links. The first explains what the sensor does, the second discusses symptoms, and the third shows in general how one is replaced.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

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If you find or suspect the sensor is the issue, here are the directions for replacement specific to your vehicle. Note: you didn't indicate engine size, so this is for the 2.5L. If that is wrong, let me know. The attached pics correlate with the directions.

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2010 Mazda 3 L4-2.5L
Removal and Replacement
Vehicle Powertrain Management Sensors and Switches - Powertrain Management Sensors and Switches - Computers and Control Systems Crankshaft Position Sensor Service and Repair Removal and Replacement
REMOVAL AND REPLACEMENT
CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [LF, L5]

Removal

1. Remove the battery cover. See: Battery > Removal and Replacement

2. Disconnect the negative battery cable.

3. Perform the following procedure for easier access.
a. Remove the under cover.

b. Remove the splash shield.

4. Disconnect the CKP sensor connector.

5. Remove the CKP sensor.

pic 1

Installation

CAUTION:
- When foreign material such as an iron chip is on the CKP sensor, it can cause abnormal output from the sensor because of flux turbulence and adversely affect the engine control. Be sure there is no foreign material on the CKP sensor when replacing.

1. Perform the following procedure so that cylinder No.1 is at TDC.
a. Remove the wheel and tire (front right side).

b. Disconnect the drive shaft (RH) from joint shaft, set the drive shaft (RH) out of the way.(MTX)

c. Remove the cylinder block lower blind plug and install the SST.

pic 2

d. Rotate the crankshaft pulley clockwise until the crank weight contacts the SST so that cylinder No.1 is at TDC.

2. Fit the center of the CKP sensor with the fifth tooth (counting counterclockwise from the empty space A as shown in the figure) of the pulse wheel.

pic 3

3. Install the CKP sensor fitting bolts.

pic 4

4. Remove the SST then install the cylinder block lower blind plug.

pic 5

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Let me know if this helps. Interestingly, when these start going bad, they may not even set a check engine light to turn on. Let me know if you have other questions.

Take care,
Joe