P0383 Fault Code

Glow Plug/Heater Indicator Circuit

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0383 fault code relates to an issue with the glow plug or heater indicator circuit. This code is triggered when the Engine Control Module (ECM) detects a malfunction in the glow plug system, which is crucial for starting diesel engines, especially in cold conditions. The glow plugs help preheat the combustion chamber to ensure efficient engine starting.

What are the symptoms of the P0383 code?

When the P0383 code is present, you might experience:

• Difficulty starting the engine, especially in cold weather.
• An illuminated check engine light on the dashboard.
• Rough idling or reduced engine performance during startup until the engine warms up.
• Increased emissions, due to incomplete combustion during starting.

What causes the P0383 code?

Several factors can contribute to the P0383 error code, including:

• Faulty glow plugs that have burned out or have a poor connection.
• A defective glow plug control module or relay that fails to properly supply power to the glow plugs.
• Issues with the wiring or connectors in the glow plug circuit, leading to short circuits or open circuits.
• A problem with the engine control module (ECM) itself, which could misinterpret the signals from the glow plug system.

How to fix P0383?

To resolve the P0383 fault code, technicians typically follow these steps:

• Inspect and test the glow plugs for any signs of failure and replace them if necessary.
• Check the glow plug control module and ensure it is functioning properly; replace it if faulty.
• Examine the wiring and connectors in the glow plug circuit for damage or corrosion, and repair any issues found.
• If all else checks out but the code persists, perform an ECM update or replacement, as it may be misreading the signals.