P1790 – OBD-II DTC

OBD-II DTC P1790 – Transmission Mechanical Failure – First And Second

DTC P1790 meaning

DTC P1790 refers to a diagnostic trouble code indicating a mechanical failure in the transmission, specifically related to the first and second gears. This code is generated when the vehicle’s onboard diagnostic system detects an issue with the transmission’s ability to engage or operate these gears properly. It is crucial for the vehicle’s performance and can affect drivability.

DTC P1790 symptoms

Common symptoms associated with DTC P1790 may include:

• Slipping transmission
• Delayed or harsh shifting
• Inability to shift into first or second gear
• Check Engine Light illuminated
• Unusual noises from the transmission

DTC P1790 causes

Several factors can lead to the triggering of DTC P1790, including:

• Low transmission fluid levels
• Worn or damaged transmission components
• Faulty transmission control module (TCM)
• Electrical issues, such as short circuits or open circuits
• Improperly adjusted or malfunctioning shift linkage

DTC P1790 seriousness

DTC P1790 is considered a serious issue as it directly impacts the vehicle’s transmission functionality. If left unaddressed, it can lead to further mechanical damage, reduced vehicle performance, and potential safety hazards while driving. It is advisable to diagnose and repair the issue promptly to ensure safe operation.

How to diagnose DTC P1790

To diagnose DTC P1790, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1790 code.
2. Check for any additional trouble codes that may provide more context.
3. Inspect the transmission fluid level and condition.
4. Examine the transmission for visible signs of damage or wear.
5. Test the transmission control module and related electrical connections.
6. Perform a road test to observe shifting behavior and symptoms.

How to fix DTC P1790 step-by-step instructions

To fix DTC P1790, follow these step-by-step instructions:

1. Check and top off the transmission fluid if low.
2. Replace the transmission fluid if it is dirty or burnt.
3. Inspect and repair any damaged wiring or connectors related to the TCM.
4. Test and replace the transmission control module if faulty.
5. Adjust or repair the shift linkage as necessary.
6. Clear the DTC using an OBD-II scanner and perform a road test to ensure the issue is resolved.

How to erase DTC P1790

To erase DTC P1790, 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. 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 check if the code reappears.

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