U1144 – OBD-II DTC

OBD-II DTC U1144 – SCP (J1850) Invalid or Missing Data for Primary Id

DTC U1144 meaning

DTC U1144 refers to a diagnostic trouble code indicating “Invalid or Missing Data for Primary Id” in vehicles equipped with the On-Board Diagnostics II (OBD-II) system. This code is specifically related to the SCP (Serial Communication Protocol) using the J1850 communication standard. It suggests that the vehicle’s control module is unable to receive valid data from another module, which may affect various systems within the vehicle.

DTC U1144 symptoms

Common symptoms associated with DTC U1144 may include:

• Illumination of the check engine light
• Communication issues between modules
• Erratic behavior of vehicle systems
• Loss of certain vehicle functions
• Diagnostic tools unable to communicate with the vehicle

DTC U1144 causes

Several factors can lead to the occurrence of DTC U1144, including:

• Faulty or damaged wiring in the communication network
• Defective control module
• Corroded or loose connectors
• Software issues or bugs in the control module
• Interference from aftermarket devices

DTC U1144 seriousness

The seriousness of DTC U1144 can vary depending on the specific vehicle and the systems affected. However, it is generally considered a moderate issue because it can lead to communication failures between critical modules, potentially impacting vehicle performance and safety. It is advisable to address this code promptly to avoid further complications.

How to diagnose DTC U1144

To diagnose DTC U1144, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC U1144.
2. Check for any additional trouble codes that may provide more context.
3. Inspect the vehicle’s wiring and connectors related to the communication network.
4. Test the affected control module for proper operation.
5. Verify the integrity of the SCP communication lines.
6. Check for software updates or reprogramming needs for the control module.

How to fix DTC U1144 step-by-step instructions

To fix DTC U1144, follow these step-by-step instructions:

1. Perform a visual inspection of the wiring and connectors for damage or corrosion.
2. Repair or replace any damaged wiring or connectors found during the inspection.
3. Test the control module for functionality and replace it if necessary.
4. Ensure that all modules are properly grounded and powered.
5. Update or reprogram the control module if software issues are identified.
6. Clear the DTC using an OBD-II scanner and perform a test drive to verify the fix.

How to erase DTC U1144

To erase DTC U1144, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Access the scanner’s menu and select the option to clear or erase trouble codes.
4. Confirm the action and wait for the scanner to complete the process.
5. Disconnect the scanner and start the vehicle 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.