STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
STEP 2. DTC recheck after resetting CAN bus lines
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is set.
Is DTC C1657 set?
Go to Step 3. This diagnosis is complete.
STEP 3. Using scan tool MB991958 other system DTC
STEP 4. Check whether the DTC is set 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 set.
Is DTC C1657 set?
Replace the electric power steering-ECU (Refer to ). Then go to Step 5. Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
STEP 5. Check whether the DTC is set 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 set.
Is DTC C1657 set?
Return to Step 1. This diagnosis is complete.