U0073
CriticalControl Module Communication Bus Off
Network/Communication System
U0073 — Instant Answer
Control Module Communication Bus Off
Severity: CRITICAL
Meaning: The entire CAN bus network has stopped communicating. Major system failure.
Safe to drive? NO if CEL is flashing. YES with caution if solid, but repair this week.
Estimated repair cost: $50 - $500
Most common causes:
- 1. CAN bus wiring short or open (35-45% of cases)
- 2. Failed module pulling bus down (10-25% of cases)
- 3. Water damage to wiring (10-25% of cases)
Symptoms
- ⚠️Multiple warning lights
- ⚠️No start
- ⚠️All gauges dead
- ⚠️No scan tool communication
Related Symptoms
Common Causes
How to Diagnose U0073
- 1Check CAN H and CAN L wiring
- 2Unplug modules one at a time to find the one pulling the bus down
- 3Check for water intrusion
- 4Inspect main wiring harness
OEM Procedures for U0073
U0073 affects the Engine Control Module. Found 146 OEM service manual procedures.
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
12 90 120 Removing and installing/replacing control unit bracket (Cooper 4-door hatchback, Cooper 2-door hatchback, 2020-2023) - Replacement: Remount DME control unit and the integrated supply module (PDM)
Showing 8 of 146 procedures
OEM Diagnostic Flowchart
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U0073 requires a scanner that reads network modules — basic code readers won't see it.
ArtiLink600
$99
DIYers working on ABS/airbag systems
View on TOPDON
ArtiDiag900 Lite
$299.24
Serious DIYers and side-hustle mechanics
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OBD2 scanner
Read codes and freeze-frame data before you guess at the fault.
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Check cranking and charging health before replacing expensive parts.
A weak battery can mimic alternator or starter problems.
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A meter is the cheapest way to rule out a bad circuit fast.
Shop on Amazon →Related Resources
Repair guides, symptom pages, and wiring diagrams related to U0073.
OEM Manual Evidence
Browse →Keyless Access Power Control Unit DTCS (2016 2017 2018 2019 2020 2021 2022) — 2013 Acura ILX Base, 2.0L Eng VIN 1 Service Manual ~ LEMON Ma...
Keyless Access Power Control Unit DTCS (2013 2014 2015) — 2013 Acura ILX Base, 2.0L Eng VIN 1 Service Manual ~ LEMON Manuals LEMON Manuals:...
Keyless Access Power Control Unit DTCS (2013 2014 2015) — 2013 Acura ILX Base, 2.4L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals:...
Keyless Access Power Control Unit DTCS (2016 2017 2018 2019 2020 2021 2022) — 2013 Acura ILX Base, 2.4L Eng VIN 2 Service Manual ~ LEMON Ma...
Related Symptoms
Browse →Exact Vehicle Hubs
Browse →Related Codes
Frequently Asked Questions
- What causes the entire CAN bus to fail?
- Usually a shorted wire or a failed module that pulls the entire bus voltage to ground. Water damage is another common cause.
- How do I diagnose a CAN bus issue?
- Measure CAN H and CAN L voltages with a multimeter. They should be ~2.5V and ~2.5V (inverted). If both are at 0V or 5V, there is a short.
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Author & Review
Written by AllOEMManuals Editorial Team. Reviewed by ASE-certified technicians and updated with factory-reference checks for fitment-sensitive steps.
This guide was drafted with AI assistance and reviewed for accuracy by a human editor.
Last updated: 2026-05-07