P1678 GMC Code - Immobilizer Powertrain Identification Failed
Quick Answer
The P1678 GMC code indicates that there has been a failure in the immobilizer powertrain identification system. Common causes include Faulty immobilizer module, Communication error between PCM and immobilizer system, Defective key or key fob. 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
- P1678 GMC indicates Immobilizer Powertrain Identification Failed.
- Common causes
- Common causes include Faulty immobilizer module, Communication error between PCM and immobilizer system, Defective key or key fob.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code P1678 GMC Description
The P1678 GMC code indicates that there has been a failure in the immobilizer powertrain identification system. The immobilizer system is designed to prevent unauthorized access to the vehicle by disabling the fuel injection system or engine starting. This specific code refers to a failure in the communication between the powertrain control module (PCM) and the immobilizer system, which can lead to the vehicle not starting or running properly.
Common Causes of P1678 GMC
- Faulty immobilizer module
- Communication error between PCM and immobilizer system
- Defective key or key fob
- Wiring issues in the immobilizer system
- Low battery voltage affecting the immobilizer system
Symptoms of P1678 GMC
- Engine cranks but does not start
- Engine starts but immediately stalls
- Inability to start the vehicle
- Security light on the dashboard stays illuminated
How to Fix P1678 GMC
- Perform a diagnostic scan using a scan tool to retrieve the error codes and pinpoint the issue.
- Check the immobilizer system components, including the module, wiring, and key fob, for any visible damage or defects.
- Reset the immobilizer system by disconnecting the vehicle's battery for a few minutes and then reconnecting it.
- If the issue persists, consider reprogramming the key to the vehicle's immobilizer system or replacing the faulty immobilizer module.
- Test the vehicle to ensure that the issue has been resolved and that the engine starts and runs properly.
Cost to Fix P1678 GMC
The cost of repairing a P1678 GMC code can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair costs for this issue can range from $200 to $500, including parts and labor. However, this estimate may be higher if the immobilizer module needs to be replaced or if additional diagnostics are required. It is recommended to consult with a qualified mechanic or dealership for a more accurate cost estimate based on your vehicle's make and model.
Need more information about the P1678 GMC code?
Need more information on how to fix the P1678 GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P1678 GMC code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P1678 GMC Code
No Frequently Asked Questions about P1678 GMC Code found.
Discuss the causes and fixes for P1678 GMC OBDII Code
Code P1678 GMC comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.