how to troubleshoot transmission codes P0720-P0799 in my Volkswagen Golf MK7 (2015-2019)

Volkswagen Golf MK8.5 (2024-Present)

Error Codes

3-5 hours

Time

medium

Difficulty

high

Severity

Error Code: P0720-P0799

3 min read

565 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 troubleshoot and fix transmission codes P0720-P0799 in Volkswagen Golf MK7 (2015-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0720-P0799

Affected Component

Transmission

Estimated Time

3-5 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical components.
•Allow the vehicle to cool down before servicing the transmission.

Symptoms

•Check engine light illuminated
•Harsh or erratic shifting
•Transmission slipping or failure to engage
•Poor acceleration or loss of power
•Unusual noises from the transmission area

Diagnostic Steps

1
Scan the vehicle's OBD-II system using a compatible scanner to confirm the presence of codes P0720 to P0799.
2
Inspect the transmission fluid level and condition; look for contamination or a burnt smell.
3
Examine wiring and connectors related to the transmission speed sensors for signs of damage or corrosion.
4
Test the transmission speed sensors (Input and Output) using a multimeter to ensure they are functioning within specifications.
5
Check for any updates or recalls related to the transmission control module (TCM) from the manufacturer.
6
Verify the operation of the TCM by performing a functional test with a diagnostic tool.

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
•Drain pan

Parts Required

•Transmission fluid (as per specifications)
•Transmission filter (if applicable)
•Transmission speed sensors (if faulty)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan the vehicle's OBD-II system using a compatible scanner to confirm the presence of codes P0720 to P0799.
2
Inspect the transmission fluid level and condition; look for contamination or a burnt smell.
3
Examine wiring and connectors related to the transmission speed sensors for signs of damage or corrosion.
4
Test the transmission speed sensors (Input and Output) using a multimeter to ensure they are functioning within specifications.
5
Check for any updates or recalls related to the transmission control module (TCM) from the manufacturer.
6
Verify the operation of the TCM by performing a functional test with a diagnostic tool.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is on a level surface and secured with wheel chocks.
Disconnect the battery to prevent electrical shorts.

2. Fluid Inspection and Replacement

Check Fluid Condition:
- Remove the transmission dipstick (if applicable) and inspect the fluid.
- If the fluid is low or contaminated, proceed to replace it.
Fluid Replacement:
- Drain the old transmission fluid using a drain pan.
- Replace the transmission filter if applicable.
- Refill with the manufacturer-recommended transmission fluid (consult owner's manual for specifications).

3. Sensor Testing and Replacement

Access Speed Sensors:
- Locate the input and output speed sensors on the transmission.
- Disconnect the electrical connectors.
Test Sensors:
- Use a multimeter to measure resistance according to specifications (usually within a specified range, consult service repair manual).
- If outside specifications, replace the faulty sensor.
Replace Sensors (if necessary):
- Remove the damaged sensor using a socket set.
- Install the new sensor and reconnect the electrical connector.

4. Wiring Inspection and Repair

Visual Inspection:
- Inspect wiring harnesses associated with the transmission for frayed wires or corrosion.
Repair or Replace Wiring:
- If damaged, cut and splice new wiring to restore connections, ensuring proper insulation.
- Use heat shrink tubing to protect the splices.

5. Reconnect and Test

Reconnect the battery.
Clear any stored codes using the OBD-II scanner.
Start the vehicle and check for any reoccurring codes.