P1400 – OBD-II DTC

OBD-II DTC P1400 – Glow Plug Monitor Fault (Bank #1)

DTC P1400 meaning

DTC P1400 refers to a fault in the glow plug monitor system for Bank #1 in diesel engines. This diagnostic trouble code indicates that the engine control module (ECM) has detected an issue with the glow plug system, which is responsible for preheating the combustion chamber to facilitate easier starting in cold conditions. The glow plug monitor fault suggests that the ECM is unable to properly assess the status or performance of the glow plugs in Bank #1.

DTC P1400 symptoms

Common symptoms associated with DTC P1400 may include:

• Difficulty starting the engine, especially in cold weather
• Increased engine cranking time
• Rough idling or misfiring during initial startup
• Illumination of the check engine light
• Decreased fuel efficiency

DTC P1400 causes

Several factors can lead to the triggering of DTC P1400, including:

• Faulty glow plugs in Bank #1
• Defective glow plug relay
• Wiring issues, such as damaged or corroded connectors
• Faulty engine control module (ECM)
• Issues with the glow plug control circuit

DTC P1400 seriousness

The seriousness of DTC P1400 can vary depending on the symptoms experienced. While it may not cause immediate engine damage, it can lead to:

• Increased emissions due to incomplete combustion
• Potential for engine starting issues, especially in colder climates
• Long-term wear on the engine components due to poor combustion

It is advisable to address this code promptly to ensure optimal engine performance and reliability.

How to diagnose DTC P1400

To diagnose DTC P1400, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1400 code.
2. Inspect the glow plugs in Bank #1 for physical damage or wear.
3. Check the glow plug relay for proper operation.
4. Examine the wiring and connectors for signs of corrosion or damage.
5. Test the glow plug control circuit for continuity and proper voltage.
6. Consider performing a visual inspection of the ECM for any signs of damage.

How to fix DTC P1400 step-by-step instructions

To fix DTC P1400, follow these step-by-step instructions:

1. Disconnect the battery to ensure safety while working on the electrical system.
2. Replace any faulty glow plugs in Bank #1.
3. Replace the glow plug relay if it is found to be defective.
4. Repair or replace any damaged wiring or connectors in the glow plug circuit.
5. Reconnect the battery and clear the DTC using an OBD-II scanner.
6. Start the engine and monitor for any reoccurrence of the P1400 code.

How to erase DTC P1400

To erase DTC P1400, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the engine to ensure the code does not return.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.