P0721 2018 GMC Sierra Code - Transmission Output Speed Sensor Performance
Quick Answer
The P0721 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates an issue with the transmission output speed sensor's performance. Common causes include Faulty transmission output speed sensor, Damaged wiring or connectors, Issues with the PCM. 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
- P0721 2018 GMC Sierra indicates Transmission Output Speed Sensor Performance.
- Common causes
- Common causes include Faulty transmission output speed sensor, Damaged wiring or connectors, Issues with the PCM.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code P0721 2018 GMC Sierra Description
The P0721 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates an issue with the transmission output speed sensor's performance. The transmission output speed sensor is a crucial component that monitors the speed of the output shaft of the transmission. This information is used by the vehicle's powertrain control module (PCM) to determine shift points, torque converter lockup, and other transmission functions.
Common Causes of P0721 2018 GMC Sierra
- Faulty transmission output speed sensor
- Damaged wiring or connectors
- Issues with the PCM
- Transmission fluid contamination
- Mechanical issues within the transmission
Symptoms of P0721 2018 GMC Sierra
- Erratic shifting
- Harsh engagements
- Transmission slippage
- Decreased fuel efficiency
- Illuminated check engine light
How to Fix P0721 2018 GMC Sierra
- Diagnose the issue using a scan tool to confirm the P0721 code and perform a visual inspection of the transmission output speed sensor and related components.
- Test the transmission output speed sensor using a multimeter to check for proper resistance and voltage readings.
- Replace the transmission output speed sensor if it is found to be faulty. Ensure proper installation and secure wiring connections.
- Clear the DTC and test drive the vehicle to verify that the issue has been resolved.
- If the problem persists, further diagnostics may be necessary to identify any underlying issues with the transmission system.
Cost to Fix P0721 2018 GMC Sierra
The typical repair costs for addressing a P0721 code on a 2018 GMC Sierra can range from $150 to $400, including parts and labor. However, specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It is advisable to check local rates for a more precise estimate. Keep in mind that rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less.
Need more information about the P0721 2018 GMC Sierra code?
Need more information on how to fix the P0721 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0721 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P0721 2018 GMC Sierra Code
1. What are the common symptoms of OBDII code P0721 in a 2018 GMC Sierra?
- Common symptoms include erratic speedometer readings, harsh shifting, and the transmission going into limp mode.
2. What does OBDII code P0721 mean for a 2018 GMC Sierra?
- OBDII code P0721 indicates a performance issue with the transmission output speed sensor in the vehicle.
3. What are some possible causes of OBDII code P0721 in a 2018 GMC Sierra?
- Potential causes include a faulty transmission output speed sensor, damaged wiring or connectors, or issues with the transmission control module.
4. How can I diagnose OBDII code P0721 in my 2018 GMC Sierra?
- Diagnosis typically involves using a scan tool to read the code, testing the transmission output speed sensor, and inspecting related wiring for damage.
5. Can I continue driving my 2018 GMC Sierra with OBDII code P0721?
- It is not recommended to continue driving with this code as it can lead to further transmission issues and potential safety concerns.
6. How is OBDII code P0721 in a 2018 GMC Sierra typically repaired?
- Repair often involves replacing the faulty transmission output speed sensor, repairing or replacing damaged wiring, and clearing the code from the vehicle's computer.
7. Are there any DIY tips for addressing OBDII code P0721 in a 2018 GMC Sierra?
- DIY enthusiasts may attempt to replace the transmission output speed sensor themselves, but it is recommended to have the vehicle properly diagnosed by a professional.
8. Can resetting the OBDII code P0721 in a 2018 GMC Sierra fix the issue temporarily?
- Resetting the code may temporarily clear the warning light, but if the underlying issue with the transmission output speed sensor is not addressed, the code is likely to return.
9. How much does it typically cost to repair OBDII code P0721 in a 2018 GMC Sierra?
- Repair costs can vary depending on the extent of the issue, but replacing a transmission output speed sensor can range from $100 to $300, including parts and labor.
10. Is OBDII code P0721 a common issue in 2018 GMC Sierra vehicles?
- While not extremely common, issues with the transmission output speed sensor leading to OBDII code P0721 can occur in 2018 GMC Sierra models and should be addressed promptly to prevent further damage.
Discuss the causes and fixes for P0721 2018 GMC Sierra OBDII Code
Code P0721 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.