U0073: How to Diagnose & Fix — Control Module Communication Bus Off
2 vehicles · 2 makes · $150-$1,600 repair
How to diagnose and fix U0073: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Cadillac XTS · 2013–2019
The Safety Alert Seat uses haptic (vibration) motors in the left and right seat bolsters to pulse warnings for lane departure, blind spot, and forward collision. One side commonly stops vibrating (left or right only), or the system randomly switches between vibrate and chime. The documented weak point is a wire breaking where it enters the haptic motor assembly. Because GM ties this hardware into the driver-assist suite, a failed seat motor frequently also triggers a 'Service Driver Assist System' message.
Common Symptoms
- No vibration on one side of seat
- Seat randomly switches to chime instead of buzz
- Service Driver Assist System message
- Lane-departure/blind-spot light flashes but no buzz
- Inconsistent forward-collision haptic
How to Fix
Confirm the dead side by triggering lane-departure to each side; if only one bolster pulses, the opposite motor/wire has failed. Replace the affected seat haptic vibration motor (left or right bumper-alert motor) and repair the broken wire at the motor entry. If the seat hardware checks out, scan the BCM for driver-assist codes and update software, since a glitch can mimic the failure. As a stopgap, owners can switch Alert Type to 'beeps' in the menu to restore audible warnings.
Sources for this issue (1)
Chevrolet Malibu · 2008–2012
The 2008-2012 Malibu electric power steering system can suddenly lose assist, reverting to heavy manual steering. The EPS motor, controller, or steering column torque sensor fails. GM issued a special coverage program (10 years/150,000 miles) for this issue. When EPS fails, a warning message and chime sound, and the steering becomes very heavy at low speeds.
Common Symptoms
- Power Steering warning message on DIC
- Steering suddenly becomes very heavy
- Service ESC warning light
- Steering assist intermittent, especially in cold weather
- Steering wheel difficult to turn at parking speeds
How to Fix
Sources for this issue (1)
Chevrolet Malibu · 2013–2024
The 2013+ Malibu uses an electric power steering (EPS) system with a column-mounted motor that is prone to failure. The motor develops internal faults causing intermittent or complete loss of power steering assist, making the car extremely difficult to steer at low speeds. GM issued TSB 18-NA-205 and NHTSA investigated numerous complaints. The steering column module and torque sensor can also fail, triggering a "Service Power Steering" message on the DIC.
Common Symptoms
- "Service Power Steering" message on DIC
- Steering suddenly becomes very heavy
- Intermittent loss and return of power assist
- Steering wheel jerks or pulls to one side
- Warning light clears after restart but returns
How to Fix
Have the EPS motor and torque sensor diagnosed with a scan tool — the module stores specific fault codes. Replacement of the EPS motor assembly costs $400-$800 for parts and $200-$400 for labor. In some cases, a software recalibration of the EPS module resolves intermittent faults. Check for applicable GM TSBs, as some vehicles may qualify for extended warranty coverage. Never ignore a power steering warning — sudden loss of assist at highway speed is a safety hazard.
Sources for this issue (1)
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U0073 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0073 mean?
U0073 stands for "Control Module Communication Bus Off." U0073 means the vehicle's communication bus has shut down, or 'gone off,' meaning a control module detected so many errors on the network that it stopped transmitting to protect the bus. On a CAN network, repeated faulty signals cause a module to take itself offline, which can cascade into multiple warning lights and disabled features. This is a network/wiring code rather than a single failed sensor, and it usually points to a wiring short, a defective module flooding the bus, or a power/ground issue affecting communication. It often requires checking the whole bus circuit, not just one part.
What are the most common causes of U0073?
The most common causes of U0073 are: Short to power or ground on the CAN bus wiring, CAN high/low wires shorted together, A failing module continuously corrupting bus traffic, Corroded, loose, or damaged bus connectors, Loss of power or ground to a network module, Faulty gateway/central communication module, Improper or missing bus terminating resistor. The specific cause varies by vehicle.
How much does it cost to fix U0073?
Repair costs for U0073 range from $150 to $1,600, depending on the vehicle and root cause.
Which vehicles are affected by U0073?
Au7o has documented U0073 across 2 vehicle models from 2 manufacturers: Cadillac, Chevrolet.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.