U0073
A module found its data network (bus A) switched off or not working
Severity: Inspect soonModule network (CAN bus) communication codes
Modern vehicles have many control modules (engine, transmission, ABS, airbags, body) that share information over a wired network, usually a two-wire CAN bus. U codes mean a module stopped hearing from another module, or received a message it could not trust. The fault is often in power, ground or wiring rather than in the module named by the code.
How these codes differ
- Lost-communication codes (for example U0100 for the engine computer, U0101 for the transmission module, U0121 for the ABS module and U0140 for the body control module) are set by the module doing the listening and name the module it cannot hear. The named module is the suspect, but so are its fuse, power feed, ground and network wires.
- Invalid-data codes (U0400 range, such as U0401 for data from the engine computer) mean messages arrive but fail a check. That points more toward the sending module or one of its sensors than toward the wiring.
- Bus-level codes (for example U0001 for the high-speed CAN bus or U0073 for a communication bus that has shut off) concern the network itself. CAN uses two twisted wires with a 120-ohm resistor at each end, so a short, an open wire or a failed terminating resistor can take down every module on that bus at once.
- The pattern across modules matters more than any one code: several modules all reporting that they lost the same module points to that module or its power and ground; many unrelated lost-communication codes at once points to the bus wiring or something shorting the bus.
- U1xxx and U2xxx codes are manufacturer-specific, so their meaning has to come from the carmaker's definition.
Codes that show up together
- Several U codes plus codes from different modules for what looks like one problem: different modules can each set a code for the same underlying fault, so find what they have in common (one silent module, a shared power or ground, or the bus wiring) before replacing any module.
Module network (CAN bus) communication codes
U0100
Lost communication with the engine or powertrain computer
Severity: Inspect soonU0101
Lost communication with the transmission computer
Severity: Inspect soonU0121
Lost communication with the anti-lock brake (ABS) module
Severity: Inspect soonU0131
Lost communication with the power steering control module
Severity: Inspect soonU0140
Lost communication with the body control module
Severity: Inspect soonU0401
A module received invalid data from the engine or powertrain computer
Severity: Severity not verifiedU0402
A module received invalid data from the transmission computer
Severity: Inspect soonU0415
A module received invalid data from the anti-lock brake (ABS) module
Severity: Inspect soonU3000
Manufacturer code: on Ford, Honda, Acura and Mazda, the module that stored it found a fault inside itself
Severity: Inspect soonU0001
A module reports a fault on the high-speed CAN bus itself, the main data network that links the engine, transmission, brake and steering computers
Severity: Inspect soonU0151
Lost communication with the restraints (airbag) control module
Severity: Inspect soonU0155
Lost communication with the instrument panel cluster
Severity: Inspect soonU0170
Lost communication with restraints system sensor A
Severity: Inspect soonU0404
A module received implausible data from the gear shift (shifter) module
Severity: Inspect soonU0416
A module received implausible data from the stability control (vehicle dynamics) module
Severity: Inspect soonU0418
A module received implausible data from the brake system (ABS) control module
Severity: Inspect soonU0420
A module received implausible data from the power steering control module
Severity: Inspect soonU0422
A module received implausible data from the body control module
Severity: Severity not verifiedU1000
Manufacturer code: on Nissan and Infiniti a module saw an error on the CAN network; on older GM vehicles it is a Class 2 serial data fault
Severity: Inspect soonU3003
Manufacturer code: on Ford, Lincoln, Mazda and Honda, the module that stored it saw its battery supply voltage outside the allowed range, usually too low
Severity: Inspect soonU0002
The high-speed CAN bus is still working but with too many errors or a poor signal
Severity: Inspect soonU0103
A module lost communication with the electronic gear shift module, the computer behind the shifter
Severity: Inspect soonU0146
A module lost communication with gateway module A, which passes messages between the vehicle networks
Severity: Inspect soonU0293
A module lost communication with the hybrid or EV powertrain control module on the vehicle network
Severity: Inspect soonU0412
A module received invalid data from the battery energy control module, the computer that manages the high-voltage battery
Severity: Inspect soonU1110
Manufacturer code: on Jeep and Dodge, U1110 means a module lost the vehicle speed message it expects over the vehicle network
Severity: Inspect soonU1120
Manufacturer code: on Jeep and Dodge, U1120 means a module lost the wheel distance message it expects over the vehicle network
Severity: Inspect soonU0109
Lost communication with the fuel pump control module
Severity: Inspect soonU0111
Lost communication with the battery energy control module
Severity: Inspect soonU0141
Lost communication with the body control module
Severity: Inspect soonU0164
Lost communication with the HVAC control module
Severity: Severity not verifiedU18A2
On Chevrolet, U18A2 means the engine computer lost communication with the fuel pump driver control module
Severity: Inspect soonU2023
On Ford, U2023 means a module received a fault status message from another module on the network
Severity: Inspect soonU2100
On Ford and Lincoln, U2100 means a module reports that its initial configuration is not complete
Severity: Inspect soonU2603
On the Chevrolet Volt, U2603 is the first of a block of codes set when the Battery Energy Control Module loses communication with the battery interface modules
Severity: Inspect soonU2624
On the Chevrolet Volt, U2624 is part of the Battery Energy Control Module communication code block, stored with U2603-U2606 and P1E00
Severity: Inspect soonU0102
U0102 is a generic network code: a module lost communication with the transfer case control module on a four-wheel or all-wheel-drive vehicle
Severity: Inspect soonU0122
U0122 is a generic network code: a module lost communication with the vehicle dynamics control module, which runs stability control and often shares the ABS hardware
Severity: Inspect soonU0129
U0129 is a generic network code: a module on the vehicle network lost communication with the brake control module (ABS or stability module), usually stored by the engine, body or instrument computer
Severity: Inspect soonU0428
U0428 is a generic network code: a module received invalid data from the steering angle sensor or steering angle control module, which stability control and power steering rely on
Severity: Inspect soonU1010
On Ford hybrids such as the Maverick Hybrid, U1010 is a manufacturer network code reported by dealers as invalid internal control module monitoring data received from the hybrid powertrain control module
Severity: Inspect soonU1262
On Ford vehicles of the early 2000s, U1262 is a network code meaning the SCP communication bus (the standard corporate protocol data link between modules) has a fault, often stored in the instrument cluster
Severity: Inspect soonU2105
On Chevrolet and other GM vehicles with the GMLAN network, U2105 is a network code meaning another module lost communication with the engine control module
Severity: Inspect soonU3006
On Honda and Acura vehicles, U3006 is a network code set when a control module sees a power supply problem on its input power circuit (low voltage or an open circuit), with the suffix such as -13 or -16 showing which
Severity: Inspect soonU0104
A module on the network stopped hearing the cruise control module
Severity: Severity not verifiedU0212
A module on the network stopped hearing the steering column control module
Severity: Inspect soonU0423
A module received invalid data from the instrument panel control module
Severity: Severity not verifiedU1504
On Chrysler vehicles, U1504 is a network code for an implausible message length from the steering angle sensor
Severity: Inspect soonU2107
On Chevrolet and other GM vehicles with the GMLAN network, U2107 means the engine control module lost communication with the body control system
Severity: Inspect soonU0126
A module on the network stopped hearing the steering angle sensor
Severity: Inspect soonU0159
A module on the network stopped hearing the parking assist control module
Severity: Severity not verifiedU029D
A module on the network stopped hearing the first (upstream) NOx sensor module
Severity: Inspect soonU029E
A module on the network stopped hearing the second (downstream) NOx sensor module
Severity: Inspect soonU0452
A module received data from the restraints (airbag) control module that did not make sense
Severity: Inspect soonU1001
On Nissan vehicles, U1001 is a CAN network communication code, stored when control units cannot communicate over the CAN lines
Severity: Inspect soonU1004
On Hyundai hybrids, U1004 is a CAN communication code for the hybrid control network, typically stored with U0293 lost communication with the hybrid powertrain control module
Severity: Inspect soonU1267
On Chrysler, Jeep and Ram vehicles, U1267 means the electronic shift module is sending no valid data on the CAN network
Severity: Inspect soonU1424
On Chrysler, Dodge, Jeep and Ram vehicles, U1424 means a module received an implausible engine torque signal
Severity: Inspect soonU160F
On GM trucks and SUVs, U160F means lost communication with brake system control module 1 on CAN bus 1
Severity: Inspect soonU1403
On Chrysler vehicles, U1403 means the fuel level signal received over the network is implausible
Severity: Severity not verifiedU1428
On Jeep, U1428 is set when the transmission control module receives an engine torque value from the engine computer that it judges inaccurate or stuck
Severity: Inspect soonP1698
On Dodge and Chrysler, the engine computer stopped receiving messages from the transmission computer on the vehicle data bus
Severity: Severity not verifiedU0029
Vehicle communication network bus A performance fault
Severity: Severity not verifiedU010C
Lost communication with the turbocharger/supercharger control module
Severity: Severity not verifiedU0184
Lost communication with the radio
Severity: Severity not verifiedU0199
Lost communication with door control module A
Severity: Severity not verified
Sources and review
- Final Regulation Order: 13 CCR §1968.2, Malfunction and Diagnostic System Requirements (OBD II), 2004 and subsequent model-year passenger cars, light-duty trucks and medium-duty vehicles (2015 amendments)
- Introduction to the Controller Area Network (CAN), Application Report SLOA101B
- Diagnostic Trouble Codes Explained: How to Manage DTCs
- SAE J2012_202509: Diagnostic Trouble Code Definitions (standard abstract)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error