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 » U0117

Code U0117

Symptoms

• Check Engine Light is on

• Vehicle may not start

• Reduced fuel efficiency

Common Causes

• Faulty Battery Energy Control Module A

• Open or shorted CAN bus wiring

• Faulty PCM

Glossary

PCM: Powertrain Control Module

CAN bus: Controller Area Network bus

Related Codes

• U0100

• U0121

Laymans terms

Your car has a computer that talks to different parts to make sure everything works. U0117 means one part isn't hearing from another part like it should.

Explanation

U0117 indicates a loss of communication with the vehicle's 'Battery Energy Control Module A'.

Technical description

The U0117 code is set when the vehicle's control modules, such as the Powertrain Control Module (PCM), lose communication with the Battery Energy Control Module A. This communication is conducted over the Controller Area Network (CAN) bus.

Diagnosis steps

• Verify the code with an OBD-II scanner.

• Inspect the CAN bus wiring for damage.

• Test the Battery Energy Control Module A for faults.

Repair procedures

• Repair or replace damaged CAN bus wiring.

• Replace the Battery Energy Control Module A if faulty.

• Reprogram or replace the PCM if necessary.

Tools required

• OBD-II Scanner

• Multimeter

• CAN bus analyzer

Estimated repair cost

$150 - $500

Difficulty level

Moderate

Commonly affected vehicles

• Toyota Prius

• Chevrolet Volt

• Nissan Leaf

Preventive measures

• Regularly inspect wiring for damage.

• Ensure battery terminals are clean and secure.

• Perform routine diagnostic checks.

Error code type

Communication Error

User experience recommendations

• Avoid driving until the issue is diagnosed.

• Consult a professional mechanic for a thorough inspection.

Warranty information

Check with the vehicle manufacturer for warranty coverage on electronic components.

Historical data

This code has become more common with the increase in hybrid and electric vehicles due to their complex electronic systems.

Urgency level

High – This issue can affect vehicle performance and should be addressed promptly.

Legal and safety notice

Driving with this code may lead to vehicle performance issues and could be unsafe. Check local regulations regarding vehicle emissions and safety compliance.

Testing conditions

• Vehicle ignition in 'ON' position.

• Battery fully charged.

Component location

The Battery Energy Control Module A is usually located near the vehicle's battery pack.

FAQs

Q: Can I drive with a U0117 code?
A: It's not recommended as it may affect vehicle performance and safety.

Q: Does the U0117 code affect fuel efficiency?
A: Yes, it can lead to reduced fuel efficiency due to improper communication between modules.

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

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