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U-codes, Network / Communications
CAN bus, module communications and network faults.
What are U-codes?
U-codes are network and communications codes, they appear when one or more of your car's control modules has lost communication with another over the CAN bus (Controller Area Network). Modern vehicles have tens of modules constantly exchanging data; U-codes fire when that communication breaks down.
General context
U-codes frequently appear alongside other fault codes when a module goes offline or loses power. The root cause is typically the underlying fault, a failed module, wiring fault, or blown fuse. Diagnosis of network faults usually requires manufacturer-level diagnostic tools.
We don't assign per-code severity ratings. Whether a specific fault is urgent depends on the cause on a specific vehicle, which only a qualified mechanic can determine.
Most common U-codes
The U-codes drivers look up most often.
All U-codes (524)
Page 1 of 6 U0009 High Speed CAN Communication Bus (-) shorted to Bus (+) U0018 Medium Speed CAN Communication Bus (-) shorted to Bus (+) U0027 Low Speed CAN Communication Bus (-) shorted to Bus (+) U0029 Vehicle Communication Bus A - Fault U0036 Vehicle Communication Bus A (-) shorted to Bus A (+) U0045 Vehicle Communication Bus B (-) shorted to Bus B (+) U0046 Vehicle Communication Bus D - Fault U0054 Vehicle Communication Bus C (-) shorted to Bus C (+) U0063 Vehicle Communication Bus D (-) shorted to Bus D (+) U0072 Vehicle Communication Bus E (-) shorted to Bus E (+) U0073 Control Module Communication Bus "A" Off U0074 Control Module Communication Bus "B" Off U0132 Lost Communication with Ride Level Control Module U0133 Lost Communication with Active Roll Control Module U0134 Lost Communication with Rear Power Steering Control Module U0135 Lost Communication with Front Differential Control Module U0136 Lost Communication with Rear Differential Control Module U0137 Lost Communication with Trailer Brake Control Module U0138 Lost Communication with All Terrain Control Module U0139 Lost Communication with Suspension Control Module "B" U0141 Lost Communication With Body Control Module "A" U0142 Lost Communication With Body Control Module "B" U0143 Lost Communication With Body Control Module "C" U0144 Lost Communication With Body Control Module "D" U0145 Lost Communication With Body Control Module "E" U0151 Lost Communication with Restraints Control (RCM) Module U0152 Lost Communication with Side Restraints Control Module (Left) U0153 Lost Communication with Side Restraints Control Module (Right) U0154 Lost Communication with Restraints Occupant Sensing Control Module U0212 Lost Communication With Steering Column Control Module U0213 Lost Communication With Mirror Control Module U0250 Lost Communication With Impact Classification System Module U0251 Lost Communication With Running Board Control Module B U0252 Lost Communication With Lighting Control Module Rear B U0253 Lost Communication With Accessory Protocol Interface Module U0254 Lost Communication With Remote Start Module U0255 Lost Communication With Front Display Interface Module U0256 Lost Communication With Front Controls Interface Module "A" U0257 Lost Communication With Front Controls/Display Interface Module U0259 Lost Communication With Special Purpose Vehicle Control Module A U025A Lost Communication With Special Purpose Vehicle Control Module B U025B Lost Communication With Special Purpose Vehicle Control Module C U025C Lost Communication With Special Purpose Vehicle Control Module D U025D Lost Communication With Front Controls Interface Module "B" U0260 Lost Communication With Seat Control Switch Module A U0261 Lost Communication With Seat Control Switch Module B U0293 Lost Communication With Hybrid Powertrain Control Module U0300 Internal Control Module Software Incompatibility U0302 Software Incompatibility With Transmission Control Module U0303 Software Incompatibility With Transfer Case Control Module U0304 Software Incompatibility With Gear Shift Control Module "A" U0305 Software Incompatibility With Cruise Control Module U0306 Software Incompatibility With Fuel Injector Control Module U0307 Software Incompatibility With Glow Plug Control Module U0308 Software Incompatibility With Throttle Actuator Control Module U0309 Software Incompatibility With Alternative Fuel Control Module U0310 Software Incompatibility With Fuel Pump Control Module U0311 Software Incompatibility With Drive Motor Control Module
(DMCM) U0312 Software Incompatibility With Battery Energy Control Module
A U0313 Software Incompatibility With Battery Energy Control Module
B U0314 Software Incompatibility With Four-Wheel Drive Clutch Control Module U0315 Software Incompatibility With Anti-Lock Brake System Control Module U0316 Software Incompatibility With Vehicle Dynamics Control Module U0317 Software Incompatibility With Park Brake Control Module U0318 Software Incompatibility With Brake System Control Module U0319 Software Incompatibility With Steering Effort Control Module U0320 Software Incompatibility With Power Steering Control Module U0321 Software Incompatibility With Suspension Control Module "A" U0322 Software Incompatibility With Body Control Module (BCM) U0323 Software Incompatibility With Instrument Panel Control Module U0324 Software Incompatibility With HVAC Control Module U0326 Software Incompatibility With Vehicle Immobilizer Control Module U0327 Software Incompatibility With Vehicle Security Control Module U0328 Software Incompatibility With Steering Angle Sensor Module U0329 Software Incompatibility With Steering Column Control Module U0330 Software Incompatibility With Tire Pressure Monitor Module U0331 Software Incompatibility With Body Control Module (BCM) "A" U0332 Software Incompatibility With Multi-axis Acceleration Sensor Module U0333 Software Incompatibility With Gear Shift Control Module "B" U0335 Software Incompatibility With Hybrid Battery Pack Sensor Module U0336 Software Incompatibility with Restraints Control Module U0402 Invalid Data Received From Transmission Control Module (TCM) U0403 Invalid Data Received From Transfer Case Control Module U0404 Invalid Data Received From Gear Shift Control Module "A" U0405 Invalid Data Received From Remote Keyless Entry Control Module U0406 Invalid Data Received From Fuel Injector Control Module U0407 Invalid Data Received From Glow Plug Control Module U0408 Invalid Data Received From Throttle Actuator Control Module U0409 Invalid Data Received From Alternative Fuel Control Module U040B Invalid Data Received From Exhaust Gas Recirculation Control Module "A" U040C Invalid Data Received From Exhaust Gas Recirculation Control Module "B" U040D Invalid Data Received From Turbocharger/Supercharger Control Module "A" U040E Invalid Data Received From Turbocharger/Supercharger Control Module "B" U040F Invalid Data Received From Reductant Control Module U0410 Invalid Data Received From Fuel Pump Control Module U0411 Invalid Data Received From Drive Motor Control Module (DMCM) "A" U0412 Invalid Data Received From Battery Energy Control Module "A" U0413 Invalid Data Received From Battery Energy Control Module "B" U0414 Invalid Data Received From Four-Wheel Drive Clutch Control Module U0415 Invalid Data Received From Anti-Lock Brake System (ABS) Control Module
Showing 1–100 of 520 remaining codes
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