how to fix transmission codes P0717 and P0720 on my Tesla Outback 5th Generation (2015-2019)

Subaru Outback 5th Generation (2015-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0717, P0720

3 min read

591 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0717 and P0720 transmission codes in Tesla Outback 5th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0717, P0720

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before opening the transmission fluid fill or drain plugs.

Symptoms

•Check engine light illuminated
•Erratic shifting or transmission slipping
•Delayed engagement of gears
•Poor acceleration performance
•Transmission overheating warning

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0717 and P0720.
2
Inspect the transmission speed sensors visually for damage or disconnections.
3
Check the wiring harness and connectors for corrosion or loose connections.
4
Measure the resistance of the input and output speed sensors using a multimeter.
5
Verify the transmission fluid level and condition.
6
Inspect the vehicle’s transmission control module (TCM) for any fault codes or operational issues.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Multimeter
•Socket set
•Torque wrench
•Transmission fluid

Parts Required

•Input speed sensor
•Output speed sensor
•Transmission fluid

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0717 and P0720.
2
Inspect the transmission speed sensors visually for damage or disconnections.
3
Check the wiring harness and connectors for corrosion or loose connections.
4
Measure the resistance of the input and output speed sensors using a multimeter.
5
Verify the transmission fluid level and condition.
6
Inspect the vehicle’s transmission control module (TCM) for any fault codes or operational issues.

Solution

1. Preparation

Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, transmission fluid.
Ensure the vehicle is parked on a level surface and the engine is turned off. Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Speed Sensors

Remove the Underbody Shield:
- Use a socket set to remove any bolts securing the underbody shield.
- Carefully set the shield aside.
Access Speed Sensors:
- Locate the input and output speed sensors on the transmission. The input speed sensor is usually positioned near the transmission bell housing, while the output speed sensor is at the tail shaft.
Disconnect the Sensors:
- Carefully unplug the electrical connectors from both the input and output speed sensors.
Remove the Speed Sensors:
- Use a socket or wrench to remove the bolts holding the sensors in place.
- Gently pull the sensors out of their mounting locations.
Install New Speed Sensors:
- Apply a small amount of transmission fluid to the O-ring of the new sensors.
- Insert the new sensors into their respective locations and secure them with bolts to the manufacturer’s torque specifications (typically around 8-10 ft-lbs, but refer to the service manual).
Reconnect Electrical Connectors:
- Plug the electrical connectors back into the new sensors.

3. Transmission Fluid Check and Replacement

Check Fluid Level:
- Remove the dipstick or fill plug, if equipped. Check fluid levels; add fluid if low.
Fluid Replacement (if necessary):
- Drain old transmission fluid by removing the drain plug (if equipped) and allow it to fully drain into an appropriate container.
- Replace the transmission fluid with the manufacturer-recommended type (typically ATF, verify specifications).
- Reinstall the drain plug with the appropriate torque.

4. Reconnect Battery and Clear Codes

Reconnect the battery terminals securely.
Use the OBD-II scanner to clear any existing fault codes from the vehicle’s computer.