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Home/DTC Codes/Mitsubishi/Eclipse/2009-2009 2.4L I4/U0004
U0004

High Speed CAN Communication Bus (+) Low

2009-2009 Mitsubishi Eclipse 2.4L I4

High SeverityNetworkGeneric (SAE)

The 2009 Mitsubishi Eclipse is equipped with a 2.4L inline-4 engine. Below you'll find detailed u0004 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.

Description

The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.

Symptoms

  • Communication failures
  • Multiple DTCs from various modules
  • Intermittent system operation

Common Causes

  • CAN H wire shorted to ground
  • Module pulling CAN H low
  • Damaged wiring insulation
  • Water intrusion in connector

Diagnostic Steps

  1. Measure CAN H voltage
  2. Disconnect modules one at a time to find short source
  3. Inspect wiring for chafing against ground
  4. Check connectors for moisture

Repair Notes

Find and repair the short to ground on the CAN H wire. Inspect for damaged insulation.

Related Codes

U0001High Speed CAN Communication BusU0003High Speed CAN Communication Bus (+) OpenU0005High Speed CAN Communication Bus (+) High

Other Network Codes

U0004 on Other Vehicles

Mitsubishi 3000GT

1996-1996 3.0L V6 Twin Turbo

Mitsubishi 3000GT

1997-1997 3.0L V6 Twin Turbo

Mitsubishi 3000GT

1998-1998 3.0L V6 Twin Turbo

Mitsubishi 3000GT

1999-1999 3.0L V6 Twin Turbo

Mitsubishi Colt JP

2002-2002 1.3L I4 4A90

Mitsubishi Colt JP

2002-2002 1.5L I4 4A91

Mitsubishi Colt JP

2003-2003 1.3L I4 4A90

Mitsubishi Colt JP

2003-2003 1.5L I4 4A91

Common Questions

What does code U0004 mean on a 2009-2009 Mitsubishi Eclipse?

U0004 stands for "High Speed CAN Communication Bus (+) Low". The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.

What are the symptoms of U0004 on a Mitsubishi Eclipse?

Common symptoms of U0004 include: Communication failures, Multiple DTCs from various modules, Intermittent system operation.

What causes U0004 on a 2009-2009 Mitsubishi Eclipse?

Common causes of U0004 include: CAN H wire shorted to ground, Module pulling CAN H low, Damaged wiring insulation, Water intrusion in connector.

Last updated: March 2026

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