DTC Troubleshooting: U0400-66 (EPS Control Unit) (2025): Notes

DTC U0400-66  : Incorrect Signal Detection (External Intrusion)

How to use this service information .

NOTICE: 

• Before you troubleshoot, review the How to Troubleshoot .
• Confirm with the customer whether an aftermarket unit is connected. If it is connected, thoroughly inspect the location and the bus line where the unit is installed.
• If a loss of communication DTC is indicated in the CAN gateway, troubleshoot the indicated DTC first.
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    Network Communications [CAN Gateway]: Go to the indicated DTC's troubleshooting - Refer to: Network Communications DTC Troubleshooting Index (2025)