P1690 DTC Code


In the world of automotive diagnostics, trouble codes play a crucial role in identifying issues within a vehicle’s subsystems. One such code is the P1690 DTC code, which can be encountered while diagnosing a vehicle for various underlying problems. In this article, we will delve deep into the P1690 DTC code, its causes, symptoms, potential solutions, and frequently asked questions surrounding it.

Understanding the P1690 DTC Code

The P1690 Diagnostic Trouble Code (DTC) refers to an issue related to the immobilizer system in a vehicle. This code is commonly encountered in vehicles equipped with an electronic key or a key fob. When this code is triggered, it indicates that the ECM (Engine Control Module) has detected a problem with the immobilizer system, preventing the vehicle from starting or running normally.

Causes of the P1690 DTC Code

Several factors can contribute to the activation of the P1690 DTC code. Here are some common causes:

  1. Faulty Immobilizer Key: If the key or key fob used to start the vehicle is faulty or damaged, it can trigger the P1690 code.
  2. Issues with Key Recognition: Problems with the key recognition system, such as a defective antenna or immobilizer control module, can lead to the activation of this code.
  3. Wiring or Connection Problems: Faulty wiring or loose connections between various components of the immobilizer system can cause the P1690 DTC code.
  4. Faulty Engine Control Module: In some cases, a malfunctioning ECM itself can trigger this code, indicating that there is an internal issue within the module.

Symptoms of the P1690 DTC Code

When the P1690 DTC code is present, it may manifest through various symptoms, including:

  1. Engine Starting Issues: The most common symptom associated with the P1690 code is difficulty or failure to start the engine.
  2. No Cranking or Ignition: When this code is active, the engine may not crank or start at all, leaving the vehicle inoperable.
  3. Immobilizer Warning Light: In some vehicles, the immobilizer warning light may illuminate on the instrument cluster, indicating the presence of an issue with the immobilizer system.

Diagnosis and Solutions

Diagnosing and resolving the P1690 DTC code requires a systematic approach. Here are a few steps to consider:

  1. Check Immobilizer Key: Start the diagnosis by inspecting the key or key fob used to start the vehicle. Ensure it is in good condition and not damaged.
  2. Verify Key Recognition: Check if the key is being recognized by the immobilizer system. Ensure that the antenna is working properly and that there are no loose connections.
  3. Inspect Wiring and Connections: Thoroughly inspect the wiring and connections associated with the immobilizer system. Look for any signs of damage, corrosion, or loose connectors. Repair or replace as necessary.
  4. Test Engine Control Module: If all other components are in proper working condition, it is essential to check the ECM for potential faults. This may require advanced diagnostic equipment and expertise. If a fault is found, repairing or replacing the ECM may be necessary.

It is recommended to consult a professional automotive technician or a dealership for an accurate diagnosis and expert assistance in resolving the P1690 DTC code.

Frequently Asked Questions (FAQs)

To provide further clarity, here are answers to some frequently asked questions related to the P1690 DTC code:

1. Can I still drive my vehicle with the P1690 code active? No, when the P1690 code is active, it typically indicates a problem with the immobilizer system, which can prevent the vehicle from starting or running normally. It is advisable to have the issue resolved before attempting to drive the vehicle.

2. Can I reset the P1690 code myself? While it is possible to reset the trouble codes using an OBD-II scanner or diagnostic tool, the P1690 code will likely reappear if the underlying issue has not been resolved. Resetting the code without addressing the cause may only provide temporary relief.

3. How much does it cost to fix the P1690 code? The cost of fixing the P1690 code can vary depending on the cause of the issue and the labor rates in your area. Additionally, if any components need replacing, their cost may also contribute to the overall repair expense. It is best to consult with a professional technician for a precise estimate.


The P1690 DTC code is a signal of trouble within the immobilizer system of a vehicle. It can manifest through engine starting issues and the illumination of the immobilizer warning light. By understanding the causes, symptoms, and possible solutions discussed in this article, vehicle owners can have a better grasp of the situation when encountering the P1690 DTC code. Professional diagnosis and assistance are recommended to effectively resolve this code and ensure optimal vehicle performance and security.

About author


Meet Sam Mitchell, your experienced and reliable guide in the complex world of car fault codes. With a robust career spanning over 15 years as a professional car mechanic, John has the skills, knowledge, and practical experience to help you navigate car fault issues with confidence.


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