This TSB applies to 2010-2012 Mazda3 vehicles with VINs lower than JM1BL******529488 (produced before Sept. 5, 2011) and 2012 Mazda5 vehicles with VINs lower than JM1CW******124931 (produced before Sept. 5, 2011).
Some Mazda vehicles may experience the MIL on with one or more of the following DTCs stored in memory:
C0051:2F (BCM) Erratic signal from steering angle sensor.
C1938 (EHPAS) Signal error from BCM.
U0422:00 (DSC) Abnormal message from BCM.
U0428:** (DSC) Abnormal message from BCM.
NOTE: If U0428 is stored, the MIL will return every time the ignition is switched on. Without U0428, the MIL turns on intermittently every time the ignition is switched on.
Since this symptom is intermittent, it may not be possible to duplicate the symptom even with the concerned steering angle sensor.
1. Verify the concern.
2. Replace the steering angle sensor with a new one.
3. Turn the ignition switch on.
4. Perform the following steps and verify that the MIL does not turn on:
a. Align the steering wheel to the center.
b. Within five to 10 seconds, turn the steering wheel completely to the right and then completely to the left, then return to center.
c. Within one to two seconds, turn the steering wheel completely to the right and then completely to the left, then return to center.
d. Repeat steps b and c one more time.
e. Verify that the MIL does not turn on.
5. Verify the repair.
