P1399 – OBD-II DTC

OBD-II DTC P1399 – Glow Plug Circuit High Input (Bank #2)

DTC P1399 meaning

DTC P1399 refers to a diagnostic trouble code indicating a high input signal from the glow plug circuit in Bank #2 of a diesel engine. This code suggests that the Engine Control Module (ECM) has detected an abnormal voltage level in the glow plug circuit, which may affect the engine’s starting and performance, especially in cold conditions.

DTC P1399 symptoms

Common symptoms associated with DTC P1399 may include:

• Difficulty starting the engine, particularly in cold weather
• Increased engine cranking time
• Rough idling or misfiring
• Decreased fuel efficiency
• Check Engine Light (CEL) illuminated

DTC P1399 causes

Several factors can lead to the triggering of DTC P1399, including:

• Faulty glow plugs in Bank #2
• Wiring issues, such as damaged or corroded connectors
• Short circuits in the glow plug circuit
• Faulty Engine Control Module (ECM)
• Issues with the glow plug relay

DTC P1399 seriousness

The seriousness of DTC P1399 can vary based on the underlying issue. While it may not cause immediate engine damage, it can lead to:

• Starting difficulties, especially in cold weather
• Increased emissions due to incomplete combustion
• Potential long-term engine performance issues

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

How to diagnose DTC P1399

To diagnose DTC P1399, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1399 code.
2. Inspect the glow plugs in Bank #2 for any visible damage or wear.
3. Check the wiring and connectors for signs of corrosion or damage.
4. Test the glow plug relay for proper operation.
5. Measure the voltage at the glow plugs to ensure it is within the manufacturer’s specifications.
6. Examine the ECM for any faults or updates that may be necessary.

How to fix DTC P1399 step-by-step instructions

To fix DTC P1399, follow these step-by-step instructions:

1. Disconnect the battery to ensure safety while working on the electrical system.
2. Inspect and replace any faulty glow plugs in Bank #2.
3. Repair or replace any damaged wiring or connectors in the glow plug circuit.
4. Test and replace the glow plug relay if it is not functioning correctly.
5. Reconnect the battery and clear the DTC using an OBD-II scanner.
6. Start the engine and monitor for any reoccurrence of the P1399 code.

How to erase DTC P1399

To erase DTC P1399, 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.

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