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Engine-Codes – Generic – U1817

U1817 Code - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction

Quick Answer

The U1817 diagnostic trouble code (DTC) indicates that there is a communication problem between the Hybrid Powertrain Control Module (HPCM) and the Powertrain Expansion Controller Area Network (CAN) bus. Common causes include Wiring harness issues, Faulty connectors or terminals, Malfunctioning HPCM. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
U1817 indicates Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction.
Common causes
Common causes include Wiring harness issues, Faulty connectors or terminals, Malfunctioning HPCM.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code U1817 Description

The U1817 diagnostic trouble code (DTC) indicates that there is a communication problem between the Hybrid Powertrain Control Module (HPCM) and the Powertrain Expansion Controller Area Network (CAN) bus. The Powertrain Expansion CAN bus is a communication network that connects various modules within the vehicle's powertrain system. When communication is lost between the HPCM and the Powertrain Expansion CAN bus, it can lead to a range of issues affecting the vehicle's performance and drivability.

OBDII Code U1817 - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
U1817 Code - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction

Common Causes of U1817

  1. Wiring harness issues
  2. Faulty connectors or terminals
  3. Malfunctioning HPCM
  4. Problems with the Powertrain Expansion CAN bus
  5. Software glitches or programming errors

Symptoms of U1817

  1. Loss of power or acceleration
  2. Poor fuel efficiency
  3. Illumination of the check engine light
  4. Erratic behavior of the hybrid powertrain system
  5. Inability to switch between power modes (e.g., electric mode, hybrid mode)

How to Fix U1817

  1. Perform a thorough inspection of the wiring harness and connectors to check for any damage or loose connections.
  2. Use diagnostic tools to test the HPCM and Powertrain Expansion CAN bus for proper functionality.
  3. Check for any software updates or reprogramming that may be needed to resolve communication issues.
  4. Replace any faulty components, such as the HPCM or damaged wiring, as necessary.
  5. Clear the DTC and perform a test drive to ensure that the communication problem has been successfully resolved.

Cost to Fix U1817

The cost of repairing a U1817 code can vary depending on the specific cause of the communication failure and the labor rates in your area. Typically, you can expect to pay anywhere from $200 to $800 for parts and labor to address this issue. Keep in mind that diagnostic time and labor rates can vary, so it's best to consult with a qualified mechanic or auto repair shop for a more accurate estimate based on your vehicle's make and model.

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Code U1817 Information for Specific Makes

  • U1817 Buick — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
  • U1817 Cadillac — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
  • U1817 Chevrolet — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
  • U1817 GMC — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U1817 Code

1. What are the common symptoms of OBDII code U1817?

Symptoms may include the hybrid powertrain system not functioning properly, loss of power or acceleration, warning lights illuminated on the dashboard, and potential vehicle stalling.

2. What can cause the U1817 code to trigger?

The U1817 code is typically triggered by a malfunction in the Powertrain Expansion Controller Area Network (CAN) communication system, often due to wiring issues, a faulty powertrain control module, or a problem with the hybrid powertrain control module.

3. How do I diagnose the U1817 code?

Diagnosing the U1817 code involves checking the wiring and connectors related to the hybrid powertrain control module, inspecting the powertrain CAN bus for faults, and using a scan tool to retrieve specific error codes for further troubleshooting.

4. Can I drive my vehicle with the U1817 code?

It is not recommended to drive your vehicle with the U1817 code present, as it can lead to further damage to the hybrid powertrain system and potentially unsafe driving conditions. It's best to have the issue diagnosed and repaired promptly.

5. How can I repair the U1817 code?

Repairing the U1817 code may involve repairing or replacing damaged wiring, addressing any issues with the powertrain control modules, resetting the system, and clearing the error code. It's advisable to seek assistance from a professional mechanic for proper diagnosis and repair.

6. Are there any DIY tips for fixing the U1817 code?

While some basic inspections like checking the wiring and connectors can be done by DIY enthusiasts, diagnosing and repairing the U1817 code may require specialized tools and expertise. It's recommended to consult a qualified mechanic for accurate diagnosis and repair.

7. Is the U1817 code specific to hybrid vehicles?

Yes, the U1817 code specifically relates to communication issues with the hybrid powertrain control module on Powertrain Expansion CAN Bus, which is commonly found in hybrid vehicles.

8. Can the U1817 code be intermittent?

Yes, the U1817 code can be intermittent, meaning the communication issue may come and go. It's important to address the problem even if it temporarily resolves, as it can reoccur and potentially cause more significant issues.

9. How much does it cost to repair the U1817 code?

The cost of repairing the U1817 code can vary depending on the underlying cause of the issue, the extent of the repairs needed, and the labor rates in your area. It's best to get a diagnosis from a mechanic to determine the exact cost.

10. If the U1817 code is cleared, will it come back?

If the underlying issue causing the U1817 code is not properly addressed and repaired, it is likely to return. Clearing the code without fixing the root cause will only temporarily mask the problem.

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