What is an OBD2 code?

An OBD2 (On-Board Diagnostics) code is a diagnostic trouble code (DTC) generated by your vehicle's computer system when it detects a problem. These codes help identify specific issues with your vehicle's engine, transmission, emissions, or other systems.

How do I read OBD2 codes?

To read OBD2 codes, you'll need an OBD2 scanner. Plug it into your vehicle's OBD2 port (usually located under the dashboard), turn your key to the 'ON' position, and follow your scanner's instructions to retrieve the codes. Each code starts with a letter (P, B, C, or U) followed by four numbers.

What do the different types of OBD2 codes mean?

OBD2 codes are categorized by their first letter: P (Powertrain) for engine and transmission issues, B (Body) for interior systems like airbags, C (Chassis) for mechanical systems like brakes, and U (Network) for computer and module communication problems.

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Home » OBD2 Codes » U0604

Code U0604

Symptoms

• Check Engine Light is on

• Vehicle may not start

• Loss of communication with other modules

Common Causes

• Faulty control module

• Damaged wiring or connectors

• Software glitch in the module

Glossary

OBD-II: On-Board Diagnostics, a standardized system for vehicle diagnostics.

Control Module: An electronic device that manages various functions in the vehicle.

Related Codes

• U0100

• U0101

Laymans terms

This code means that one of the computers in the car isn't talking to the others correctly. It's like when one of your friends isn't answering your messages.

Explanation

The U0604 code indicates a communication error with the internal control module.

Technical description

U0604 is a diagnostic trouble code (DTC) that signifies a communication error between the internal control module and other modules within the vehicle's network. This can be due to data corruption or a failure in the communication lines.

Diagnosis steps

• Use an OBD-II scanner to verify the code.

• Inspect the wiring and connectors for damage.

• Check for any software updates for the control module.

Repair procedures

• Replace or repair damaged wiring or connectors.

• Reprogram or update the control module software.

• Replace the faulty control module if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Diagnostic software

Estimated repair cost

$150 - $1000

Difficulty level

Moderate

Commonly affected vehicles

• Ford F-150

• Chevrolet Silverado

• Toyota Camry

Preventive measures

• Regularly update vehicle software.

• Inspect wiring and connectors periodically.

• Avoid moisture exposure to electronic components.

Error code type

Communication Error

User experience recommendations

• Ensure all software updates are applied.

• Consult a professional if the problem persists.

Warranty information

Check if the control module is covered under the vehicle's warranty.

Historical data

This code has been more common in vehicles with complex electronic systems introduced in the last decade.

Urgency level

Moderate – It should be addressed soon to avoid further issues.

Legal and safety notice

Driving with unresolved communication errors may lead to safety issues. Always consult a qualified technician.

Testing conditions

• Vehicle ignition in ON position

• All modules connected and powered

Component location

The control module is typically located under the dashboard or in the engine compartment.

FAQs

Q: Can I drive with a U0604 code?
A: It's not recommended as it may lead to further issues. Get it checked as soon as possible.

Q: Will disconnecting the battery clear the U0604 code?
A: Disconnecting the battery might temporarily clear the code, but it won't fix the underlying issue.

Last updated: Jan 15, 2026 • Source: internal database

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