Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / U0072 — Vehicle Communication Bus E (-) shorted to Bus (+)

U0072 — Vehicle Communication Bus E (-) shorted to Bus (+)

Detailed page for trouble code U0072.

35,109codes
59brands
11,925generic
23,184specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

U0072

MERCEDES-BENZ U — Network/User

Vehicle Communication Bus E (-) shorted to Bus (+)

Brand: MERCEDES-BENZ
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or chafed wiring harness causing Bus- to contact Bus+
  • Corroded or water-intruded connector on Bus E
  • Faulty or failed module transceiver pulling Bus- to Bus+
  • Incorrectly installed aftermarket accessory tied into vehicle bus
  • Connector pins bent or pushed together
  • Previous repair with damaged insulation or pinched wires

Symptoms

  • Multiple communication or module warning lamps/messages
  • Features on systems that use Bus E are inoperative or intermittent
  • Loss of data from one or more modules on vehicle network
  • Additional U-codes or P-codes related to module communication
  • Possible vehicle enter limp or reduced functionality depending on affected modules

What to check

  • Read and record all current and pending DTCs and freeze frame data
  • Consult manufacturer wiring diagrams to identify Bus E modules, connectors and splice locations
  • Visual inspection of Bus E harness, connectors and related modules for damage, corrosion or water
  • Inspect for aftermarket devices or recent repairs in wiring harness areas
  • Measure continuity/resistance between Bus- and Bus+ with ignition OFF (computer disconnected if required)
  • Measure voltage on Bus lines with key ON (or use oscilloscope) to verify normal idle voltages and to see if one line is stuck

Signal parameters

  • Normal CAN-type bus idle: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each to ground) — differential ≈ 0 V
  • CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V — differential ≈ 2.0 V
  • If Bus- is shorted to Bus+, expect near-same voltage on both conductors or abnormal voltages relative to ground
  • Low resistance between Bus- and Bus+ (< 5 Ω) indicates a direct short

Diagnostic algorithm

  1. Retrieve and document all DTCs, then clear codes and see if U0072 returns. Note any other communication codes.
  2. Obtain wiring diagrams and identify all modules, connectors and splice points on Bus E.
  3. Visually inspect harness runs, connectors, and modules for damage, corrosion, rodent chew, water entry or recent repair marks.
  4. With ignition OFF and battery disconnected if recommended by manufacturer, measure resistance between Bus- and Bus+. A very low resistance indicates a short.
  5. If short present, disconnect Bus E connectors/modules progressively (gateway/junctions first) and re-check resistance after each disconnect to localize the short segment.
  6. If short is not isolated by disconnecting connectors, perform isolation using current-limited power or specialist short-finder tools per factory procedure to avoid component damage.
  7. Inspect and repair or replace damaged wiring, connectors, or grommets found in the faulty segment. Replace any module confirmed to have a failed transceiver.
  8. After repair, reconnect modules, clear codes, and verify restoration of normal bus voltages and module communication. Road-test / exercise affected systems and re-scan.
  9. If intermittent, perform wiggle tests and/or monitor with an oscilloscope while operating affected systems to reproduce fault.
  10. Document repairs and confirm no aftermarket device is tied into the bus before returning vehicle to customer.

Likely causes

  • Low resistance (direct short) between Bus- and Bus+ at a connector or splice
  • Corrosion/water in a gateway or bus junction connector creating conductive path
  • Failed transceiver inside a control module on Bus E
  • Aftermarket device or incorrect jump-start wiring connected to bus conductors
  • Wiring harness damage at body seams, grommets or near moving parts

Fault status

⚠️ Status
Bus E negative conductor shorted to Bus positive — communication on Bus E disrupted; modules on this bus may be inoperative until short is located and repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-4.0 hours

Similar codes

U0073 U0075 U0100 U0101 P0600
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .