Oil Pressure Sender – Bench Test – 2.5L NA

Overview

This procedure outlines how to bench test the oil pressure sender for a Porsche 944 with a 2.5L naturally aspirated (NA) engine. Bench testing verifies if the sender accurately outputs the correct resistance for specific oil pressures, helping diagnose faulty readings without replacing the unit prematurely. The test requires a regulated pressure source and is tailored for both pre-1985.5 (1982–85) and 1985.5 onwards (1985.5–88) models.

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

Tools Required

• Multimeter
• Regulated air pressure source (0–5 bar)
• Test leads
• Adapter fitting (M10x1.0 for Pre-85.5, M12x1.5 for 85.5 Onwards)

Parts Required

• Oil pressure sender (if replacement is needed): 944 606 201 00 (Pre-85.5) or 944 606 202 00 (85.5 Onwards)

Step-by-Step Procedure

Step 1: Remove the Oil Pressure Sender

1. Park the vehicle on a flat surface and engage the parking brake.
2. Turn the ignition switch to the OFF position to ensure safety.
3. Locate the oil pressure sender on the engine block, near the oil filter housing.
4. Disconnect the electrical leads from the sender. For Pre-85.5 models, note the lead connected to terminal “G.”
5. Using a 24mm (15/16 inch) wrench, carefully remove the sender from the engine block. Place a rag underneath to catch any oil drips.

Step 2: Set Up the Bench Test Equipment

6. Secure the oil pressure sender to a test rig or adapter fitting compatible with your model: M10x1.0 for Pre-85.5 or M12x1.5 for 85.5 Onwards models.
7. Connect the regulated air pressure source to the adapter fitting, ensuring a tight seal to prevent leaks.
8. Attach test leads to the multimeter and set it to measure resistance (ohms).
9. Connect one test lead to the sender’s terminal (“G” for Pre-85.5, main terminal for 85.5 Onwards) and the other to the sender’s body or ground terminal.

Step 3: Test the Sender at Specified Pressures

10. Apply pressure to the sender using the regulated air pressure source, starting at 0 bar, and measure the resistance with the multimeter. Compare the readings to the table below for your model year.

For Pre-85.5 models:

• 0 bar: 10.0 ohms

• 3 bar: 116.0 ohms

• 5 bar: 184.0 ohms

For 85.5 Onwards models:

• 1 bar: 29.6 ohms

• 2 bar: 65.3 ohms

• 3 bar: 98.9 ohms

• 4 bar: 133.6 ohms

• 5 bar: 184.0 ohms

11. Gradually increase the pressure to each value listed in the table, recording the resistance at each step.

Step 4: Evaluate Test Results

12. If the measured resistances match the values in the table within a tolerance of ±5 ohms, the oil pressure sender is functioning correctly.
13. If the resistances are outside the specified values or inconsistent, replace the sender with a new unit (944 606 201 00 for Pre-85.5 or 944 606 202 00 for 85.5 Onwards).

Post Procedure Checklist

• Verify all test equipment is disconnected and safely stored.
• Inspect the sender for physical damage or oil contamination before reinstalling or replacing.
• If reinstalling, apply thread sealant to the sender’s threads and torque to 35 Nm (26 ft-lbs) using a 24mm (15/16 inch) wrench.
• After reinstallation, reconnect the electrical leads and start the engine to confirm the oil pressure gauge reads 4.5–5 bar at startup and 2.5–3 bar at normal operating temperature.
• Check for oil leaks around the sender after reinstallation.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• YouTube