DTC C121A: Abnormality In Steering Wheel Sensor Initialization: Diagnosis

WARNING: This page is about a different car, the 2012 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

Required Special Tools:

MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 3.
2. NO: Repair the CAN bus lines. (Refer to TROUBLESHOOTING .) After repairing the CAN bus line, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C121A set?
1. YES: Go to Step 3.
2. NO: The procedure is complete.
STEP 3. Steering wheel sensor calibration
Perform calibration of the steering wheel sensor. (Refer to STEERING WHEEL SENSOR CALIBRATION .)

Q: Has the calibration succeeded?
1. YES: Go to Step 4.
2. NO: Replace the steering wheel sensor. (Refer to STEERING WHEEL SENSOR .) Then go to Step 4.
STEP 4. Check whether the DTC is reset.
Erase the DTC.

Q: Is DTC C121A set?
1. YES: Replace the hydraulic unit (integrated with ASC-ECU). (Refer to HYDRAULIC UNIT .) Then go to Step 5.
2. NO: The procedure is complete.
STEP 5. Check whether the DTC is reset.
Erase the DTC.

Q: Is DTC C121A set?
1. YES: Return to Step 1.
2. NO: The procedure is complete.