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Engine-Codes – Generic – P1921

P1921 Code - Transmission Range Signal

Quick Answer

The P1921 diagnostic trouble code (DTC) indicates a problem with the transmission range signal, which is essential for the proper operation of the transmission system. Common causes include Faulty transmission range sensor, Wiring or connection issues in the transmission range signal circuit, Low transmission fluid level or dirty transmission fluid. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1921 indicates Transmission Range Signal.
Common causes
Common causes include Faulty transmission range sensor, Wiring or connection issues in the transmission range signal circuit, Low transmission fluid level or dirty transmission fluid.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Aug 30, 2024
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Code P1921 Description

The P1921 diagnostic trouble code (DTC) indicates a problem with the transmission range signal, which is essential for the proper operation of the transmission system. The transmission range signal is used by the vehicle's computer to determine the gear position of the transmission, allowing for smooth shifting and optimal performance. When this signal is not functioning correctly, it can lead to issues such as harsh shifting, gear slippage, or the transmission not engaging at all. This can ultimately result in poor vehicle performance, reduced fuel efficiency, and potential damage to the transmission system if left unresolved.

OBDII Code P1921 - Transmission Range Signal
P1921 Code - Transmission Range Signal

Common Causes of P1921

  1. Faulty transmission range sensor
  2. Wiring or connection issues in the transmission range signal circuit
  3. Low transmission fluid level or dirty transmission fluid
  4. Mechanical issues within the transmission itself
  5. Electronic control module (ECM) failure

Symptoms of P1921

  1. Rough or harsh shifting
  2. Transmission slipping
  3. Inability to shift gears
  4. Delayed engagement when shifting
  5. Illumination of the Check Engine Light

How to Fix P1921

  1. Perform a diagnostic scan to confirm the P1921 code and identify the specific issue.
  2. Inspect the transmission range sensor and its wiring for any damage or loose connections.
  3. Check the transmission fluid level and condition, topping up or replacing as necessary.
  4. Test the electronic control module (ECM) for any faults or errors.
  5. Replace the transmission range sensor if it is determined to be faulty, and clear the code from the vehicle's computer.

Cost to Fix P1921

The cost of repairing a P1921 code can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair cost for a transmission range signal problem can range from $200 to $500, including parts and labor. It's important to note that additional diagnosis time or parts replacement may increase the overall cost. Be sure to consult with a qualified mechanic or repair shop for an accurate estimate based on your vehicle's make and model.

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Code P1921 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1921 Code

1. What are the common symptoms of OBDII code P1921 (Transmission Range Signal)?

The common symptoms of code P1921 include difficulty shifting gears, erratic shifting behavior, and the transmission not engaging properly.

2. What are the possible causes of OBDII code P1921?

Possible causes of code P1921 include a faulty transmission range sensor, damaged wiring or connectors related to the sensor, or issues with the transmission control module.

3. How can I diagnose OBDII code P1921?

Diagnosing code P1921 involves using a scan tool to retrieve the code, checking the transmission range sensor for proper operation, inspecting the wiring and connectors for damage, and testing the transmission control module.

4. Can OBDII code P1921 be triggered by other issues besides the transmission range sensor?

Yes, code P1921 can also be triggered by issues such as a faulty transmission control module, damaged wiring, or poor connections related to the transmission range signal.

5. What are some repair tips for addressing OBDII code P1921?

Repair tips for code P1921 include checking and repairing any damaged wiring or connectors, replacing the transmission range sensor if necessary, and ensuring proper communication between the sensor and control module.

6. Is it safe to continue driving with OBDII code P1921 present?

It is not recommended to continue driving with code P1921 present, as it can lead to further transmission issues and potential safety hazards on the road.

7. How much does it typically cost to repair OBDII code P1921?

The cost of repairing code P1921 can vary depending on the underlying cause, but it may range from $100 to $500 for parts and labor.

8. Can I reset OBDII code P1921 myself, or do I need a professional to do it?

You can attempt to reset code P1921 yourself using an OBDII scanner, but it is important to address the root cause of the issue to prevent the code from reoccurring.

9. Will OBDII code P1921 cause my vehicle to fail an emissions test?

Yes, code P1921 can cause your vehicle to fail an emissions test, as it indicates a malfunction in the transmission range signal system.

10. How can I prevent OBDII code P1921 from occurring in the future?

To prevent code P1921 from occurring in the future, it is essential to perform regular maintenance on your vehicle, including checking the transmission range sensor, wiring, and connections for any signs of damage or wear.

Discuss the causes and fixes for P1921 OBDII Code

Submit a New Comment

  • Showing code P 1921 can't clear it with my computer.IY is power train or SRS code?

    Reply to Comment

  • The P1921 code means that there is a problem with the Transmission and is not related to the SRS system.

    Reply to Comment

    • P1921 how can fix it? this code showed me sonata 2016

      Reply to Comment

      • It seems that the code P1921 is not recognized for your 2016 Hyundai Sonata. This could mean the code might be incorrect, or it could be a manufacturer-specific code that's not fully registered in the system.

        Could you double-check the code, or alternatively provide more details like the VIN or a description of the issue you are experiencing? This would help me assist you better!

        Reply to Comment