AutoCodes – Pontiac – P1678 Pontiac

P1678 Pontiac Code - Immobilizer Powertrain Identification Failed

Quick Answer

The Engine Control Module (ECM), the Powertrain Interface Module (PIM), and the Body Control Module (BCM) are integral part of the vehicle theft deterrent system. Common causes include Deterrent key not programmed to vheicle, Faulty Deterrent key, Fualty ignition switch. 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 Pontiac indicates Immobilizer Powertrain Identification Failed.
Common causes: Common causes include Deterrent key not programmed to vheicle, Faulty Deterrent key, Fualty ignition switch.
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.

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Code Popularity 2,205

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1678 Pontiac Description

The Engine Control Module (ECM), the Powertrain Interface Module (PIM), and the Body Control Module (BCM) are integral part of the vehicle theft deterrent system. The theft deterrent system authenticates the security code programmed into each of these modules to prevent unauthorized vehicle operation. This authentication process includes the following steps:
1.When the ignition is turned ON or the door is unlocked by remote key the BCM and the key exchange security data to verify the correct key is used.
2.Once the correct key has been confirmed and the ignition is turned ON, the PIM and BCM exchange data to confirm the correct BCM and PIM is being used.
3.Once the correct key, BCM, and PIM is confirmed, the PIM and ECM exchange data to allow the vehicle to start.
4.The data exchange processes conducted use various encrypted data exchanges between each of the devices.

OBDII Code P1678 Pontiac - Immobilizer Powertrain Identification Failed - AutoCodes.com — P1678 Pontiac Code - Immobilizer Powertrain Identification Failed

What does this mean?

What are the Possible Causes of the DTC P1678 Pontiac?

Deterrent key not programmed to vheicle
Faulty Deterrent key
Fualty ignition switch
Poor electrical connection for Deterrent circuit components

How to Fix the DTC P1678 Pontiac?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1678 Pontiac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 P1678 Pontiac Code

1. What does the OBDII code P1678 mean on a Pontiac?

Code P1678 indicates an issue with the immobilizer system where the Powertrain Control Module (PCM) fails to correctly identify the immobilizer signal.

2. What are the common symptoms of code P1678 in a Pontiac?

Symptoms may include the engine failing to start, the security light staying illuminated on the dashboard, and no communication between the PCM and immobilizer system.

3. What causes the P1678 code to appear on a Pontiac?

Common causes include a faulty immobilizer system, a damaged or unprogrammed key, wiring or connector issues, or a malfunctioning PCM.

4. Can a dead battery trigger the P1678 code on a Pontiac?

Yes, a dead or weak battery can cause communication issues between the immobilizer and PCM, potentially triggering this code.

5. How do I fix the P1678 code on my Pontiac?

Repairs may involve reprogramming the key, inspecting and repairing wiring or connectors, replacing a faulty immobilizer module, or reprogramming or replacing the PCM.

6. Is it safe to drive with the P1678 code active on a Pontiac?

No, it is typically not possible to drive since the engine may fail to start due to the immobilizer system preventing ignition.

7. How much does it cost to repair the P1678 code on a Pontiac?

Repair costs vary, ranging from $100 to $500 or more, depending on whether reprogramming, key replacement, or module repair/replacement is required.

8. Can I clear the P1678 code and solve the issue on my Pontiac?

Clearing the code without addressing the root cause will not fix the problem, and the code will likely return until the issue is resolved.

9. How do I diagnose the cause of the P1678 code on a Pontiac?

Diagnosis involves scanning for additional codes, inspecting the immobilizer and PCM connections, and testing the key and immobilizer system for proper communication.

10. Can a locksmith fix the P1678 code on a Pontiac?

A qualified locksmith with the proper tools may be able to reprogram the key or immobilizer system, but more complex repairs may require a dealership or specialized technician.