OBD-II code · Network
U01BD Lost Communication With DC/DC Converter Control Module C
ECU lost communication with DC/DC converter module C (steps HV battery down to 12V on hybrids/EVs). A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Is it safe to drive with U01BD?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyModule unpowered
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Dcdc Converter Module C, Can Bus
Related codes
- U0298Lost Communication With DC/DC Converter Control Module A
- U0299Lost Communication With DC/DC Converter Control Module B
- U01BALost Communication With Park Lock/Pawl Control Module
- U01BBLost Communication With Battery Charger Control Module B
- U01BCLost Communication With Charge Air Cooler Coolant Pump B
- U01BELost Communication with Drive Motor A Clutch Actuator
- U01BFLost Communication with Battery Management Control Module
- U0200Lost Communication With Door Control Module B
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.