OBD Guide
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U1004

Controller Area Network Bus Transmit Performance

U1004 is an OBD-II diagnostic trouble code meaning: Controller Area Network Bus Transmit Performance. Common causes: broken or damaged can bus wires, short circuit in can circuit. Estimated repair cost: $17–111.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–111 (est.)

Symptoms

  • Check Engine light comes on
  • Incorrect operation of the vehicle's electronic systems
  • Lost connection with some modules
  • Problems starting the engine
  • Dashboard malfunctions

Causes

  • Broken or damaged CAN bus wires
  • Short circuit in CAN circuit
  • Fault in one of the modules connected to the bus
  • Problems with module power supply
  • Corrosion of connectors

How to Fix

  1. Check the integrity of the CAN bus wiring
  2. Inspect connectors for corrosion or damage
  3. Check power supply and grounding of modules
  4. Scan all modules for errors
  5. Replace damaged components if necessary

Related codes

U1000U1001U1003

FAQ

What does the U1004 code mean?

U1004 is an OBD-II diagnostic trouble code that indicates: Controller Area Network Bus Transmit Performance

What causes a U1004 error code?

The most common causes of U1004 include: Broken or damaged CAN bus wires; Short circuit in CAN circuit; Fault in one of the modules connected to the bus; Problems with module power supply.

How do I fix a U1004 diagnostic trouble code?

To fix U1004: Check the integrity of the CAN bus wiring. Inspect connectors for corrosion or damage. Check power supply and grounding of modules. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1004?

Limited driving only, diagnose soon

How much does it cost to fix U1004?

The estimated repair cost for U1004 is $17–111. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat