Troubleshooting – Automatic Transmission

Overview

This guide helps you identify and fix common automatic transmission issues on your Porsche 944 S / S2 with the 16v engine. It covers problems like slipping, erratic shifts, delayed upshifts, or the car not moving in forward or reverse, as well as failure to downshift when you floor the accelerator. Proper diagnosis and repair are key to keeping your S / S2’s transmission running smoothly.

Pink and blue text represents links to additional resources, tools, parts, and partner websites.

Tools Required

• 10mm (3/8 inch) wrench
• Flathead screwdriver
• Container for catching transmission fluid
• Rags for cleanup

Parts Required

• Automatic Transmission Fluid (ATF), 944 300 901 00 (as specified for the Porsche 944 S / S2)

Step-by-Step Procedure

Step 1: Check and Adjust ATF Level

1. Park your Porsche 944 S / S2 on a level surface and let the engine idle in Park.
2. Locate the transaxle reservoir under the hood near the firewall on the driver’s side.
3. Remove the dipstick, wipe it clean with a rag, and reinsert it fully before pulling it out again to check the fluid level.
4. If the level is below the “Full” mark, add Automatic Transmission Fluid (944 300 901 00) through the dipstick tube until it reaches the correct level. Be careful not to overfill.

Step 2: Inspect and Clean the Main Pressure Control Valve

5. Turn off the engine and raise the car using a jack, securing it with jack stands.
6. Locate the transmission pan underneath the car, toward the rear of the engine bay.
7. Remove the pan bolts using a 10mm (3/8 inch) wrench and carefully lower the pan, catching any fluid in a container.
8. Find the main pressure control valve inside the transmission (consult the Porsche 944 Workshop Manual, Volume 3, for its exact location on the S2).
9. Remove the valve, clean it with a rag and ATF to remove any debris, and reinstall it securely.
10. Reattach the transmission pan and tighten the bolts to 20 Nm (15 ft-lbs).

Step 3: Adjust the Transaxle Throttle Cable

11. Locate the throttle cable where it connects to the transmission, near the throttle body.
12. Loosen the adjustment nut with a 10mm (3/8 inch) wrench.
13. Have a helper press the accelerator pedal fully while you adjust the cable tension so it’s snug but not overly tight.
14. Tighten the adjustment nut to secure the cable in place.

Step 4: Evaluate Transaxle Internal Condition

15. Test drive the car for 5 miles (8 km) to check if symptoms (slipping, erratic shifts, or no movement) persist.
16. If problems continue after Steps 1-3, the transaxle may have internal damage requiring professional attention.
17. Remove the transaxle by following this link to ensure this step – Transaxle Removal – of the process is followed accurately.
18. Take the transaxle to a qualified transmission specialist for rebuilding specific to the Porsche 944 S / S2.

Post Procedure Checklist

• Check the ATF level again after driving to ensure it’s still at the “Full” mark.
• Inspect under the car for any fluid leaks around the transmission pan.
• Test the transmission in all gears (Drive, Reverse, etc.) to confirm smooth operation.
• Verify downshifting occurs when the accelerator is fully depressed.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube