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 » U0106

Code U0106

Symptoms

• Engine hard to start

• Check Engine Light illuminated

• Reduced engine performance

Common Causes

• Faulty Glow Plug Control Module

• Open or shorted wiring harness

• Poor electrical connection

Glossary

ECM: Engine Control Module

GPCM: Glow Plug Control Module

Related Codes

• U0100

• U0101

Laymans terms

Your car has a computer that talks to other parts of the car to make sure everything works right. This code means one of those computers isn't talking like it should.

Explanation

The code U0106 indicates a loss of communication with the glow plug control module.

Technical description

U0106 is a diagnostic trouble code (DTC) indicating the Engine Control Module (ECM) has lost communication with the Glow Plug Control Module (GPCM). This communication is essential for proper engine operation, particularly in diesel engines that rely on glow plugs for starting.

Diagnosis steps

• Verify the code with an OBD-II scanner.

• Inspect the wiring and connectors to the Glow Plug Control Module.

• Test the Glow Plug Control Module for faults.

Repair procedures

• Repair or replace damaged wiring or connectors.

• Replace the Glow Plug Control Module if faulty.

• Clear the codes and test drive to ensure the issue is resolved.

Tools required

• OBD-II scanner

• Multimeter

• Basic hand tools

Estimated repair cost

$150 - $500

Difficulty level

Moderate

Commonly affected vehicles

• Ford F-250

• Chevrolet Silverado

• Dodge Ram 2500

Preventive measures

• Regular maintenance checks

• Ensure all electrical connections are secure

• Avoid exposure of electronic components to moisture

Error code type

Communication Error

User experience recommendations

• Have the vehicle inspected by a professional.

• Avoid driving long distances until repaired.

Warranty information

Check with your vehicle manufacturer for specific warranty coverage related to electronic components.

Historical data

U0106 has been a common code for diesel vehicles, especially in models with complex electronic systems.

Urgency level

Moderate – While the vehicle may still operate, it can lead to starting issues and should be addressed soon.

Legal and safety notice

Driving with this code may not be safe, especially in cold weather conditions where glow plugs are essential for starting.

Testing conditions

• Vehicle in park or neutral

• Engine off

Component location

The Glow Plug Control Module is typically located near the engine or firewall area in diesel vehicles.

FAQs

Q: Can I drive with code U0106?
A: It's not recommended as it may lead to starting issues, especially in cold weather.

Q: How do I clear the U0106 code?
A: After repairs, use an OBD-II scanner to clear the code and verify if it returns.

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

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