STEP 1. Scan tool MB991958 CAN bus diagnostics
STEP 2. Scan tool MB991958 data list
STEP 3. Scan tool MB991958 DTC of other systems
STEP 4. Check whether the DTC is stored again.
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is stored.
Is DTC U0121 stored?
Troubleshoot the ASC system (Refer to GROUP 35C - Troubleshooting/DTC Chart ). Then go to Step 5. Go to Step 6.
STEP 5. Check whether the DTC is stored again.
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is stored.
Is DTC U0121 stored?
Replace AWD-ECU (Refer to ). Then go to Step 6 . The procedure is complete.
STEP 6. Check whether the DTC is stored again.