Engine-CodesJeep – P1388 Jeep

P1388 Jeep Code - ASD or CNG Relay Control Circuit

Quick Answer

The P1388 Jeep diagnostic trouble code (DTC) refers to an issue with the ASD (Auto Shut Down) or CNG (Compressed Natural Gas) relay control circuit. Common causes include Faulty ASD or CNG relay, Wiring harness issues, Poor electrical connections. 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
P1388 Jeep indicates ASD or CNG Relay Control Circuit.
Common causes
Common causes include Faulty ASD or CNG relay, Wiring harness issues, Poor electrical connections.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1388 Jeep Description

The P1388 Jeep diagnostic trouble code (DTC) refers to an issue with the ASD (Auto Shut Down) or CNG (Compressed Natural Gas) relay control circuit. This code typically indicates a problem with the relay circuit that controls the ASD or CNG relay, which are crucial components in the vehicle's electrical system. The ASD relay is responsible for supplying power to essential engine components such as the fuel injectors, ignition coil, and oxygen sensors, while the CNG relay controls the flow of compressed natural gas in vehicles equipped with CNG systems.

OBDII Code P1388 Jeep - ASD or CNG Relay Control Circuit
P1388 Jeep Code - ASD or CNG Relay Control Circuit

Common Causes of P1388 Jeep

  1. Faulty ASD or CNG relay
  2. Wiring harness issues
  3. Poor electrical connections
  4. Defective powertrain control module (PCM)
  5. Environmental factors such as moisture or corrosion

Symptoms of P1388 Jeep

  1. Engine misfires
  2. Stalling or rough idling
  3. Poor acceleration
  4. Illumination of the Check Engine Light
  5. Difficulty starting the engine

How to Fix P1388 Jeep

  1. Begin by conducting a thorough visual inspection of the wiring harness and relay components to check for any visible damage or loose connections.
  2. Use a multimeter to test the continuity and voltage of the ASD or CNG relay circuit to determine if the components are functioning correctly.
  3. If the relay is found to be faulty, replace it with a new, OEM-approved relay to ensure proper operation.
  4. Clear the diagnostic trouble codes from the vehicle's computer using a diagnostic scan tool to reset the system and monitor for any recurring issues.
  5. Test drive the vehicle to verify that the symptoms associated with the P1388 code have been resolved and ensure proper engine performance.

Cost to Fix P1388 Jeep

The typical repair costs for addressing the P1388 Jeep code can range from $100 to $300, including parts and labor. However, it is essential to note that the specific diagnosis time and labor rates at auto repair shops can vary depending on various factors such as location, vehicle make and model, and engine type. Auto repair shops commonly charge between $80 and $150 per hour for labor, with rates potentially higher in metropolitan areas or at dealerships and lower at independent shops. It is advisable to obtain quotes from local shops for a more accurate estimate.

When is the Code Detected?

ECM commanded on the ASD or CNG relay and detected an open or shorted condition

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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.

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