DTC C1657: Implausible coding data: Diagnosis

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to 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 CAN BUS DIAGNOSTICS TABLE ). On completion, go to Step 2.
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.
Q: Is DTC C1657 set?
1. YES: Go to Step 3.
2. NO: This diagnosis is complete.
STEP 3. Using scan tool MB991958 other system DTC
Use scan tool to check whether the ETACS-ECU-related DTC is set or not.

Q: Is any DTC set?
1. YES: Troubleshoot for the relevant DTC.
2. NO: Go to Step 4.
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.
Q: Is DTC C1657 set?
1. YES: Replace the electric power steering-ECU (Refer to ELECTRIC POWER STEERING CONTROL UNIT (EPS-ECU) ). Then go to Step 5.
2. NO: Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
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.
Q: Is DTC C1657 set?
1. YES: Return to Step 1.
2. NO: This diagnosis is complete.