Porsche 944 Speed and Reference Sensors Part Numbers: Complete Guide

If you own a Porsche 944, the engine management system relies on two critical sensors: the speed sensor and the reference sensor. These sensors tell the DME (Digital Motor Electronics) when to fire the spark plugs and inject fuel. When they fail, the car may not start, run poorly, or stall. Knowing the correct part numbers is essential for replacement. This guide covers the part numbers for both sensors across all 944 model years and variations.

Understanding Speed vs. Reference Sensors

The speed sensor (often called the engine speed sensor) monitors crankshaft rotation speed. The reference sensor (or TDC sensor) identifies top dead center of cylinder No. 1. Both are mounted on the bell housing of the transmission, reading a trigger wheel on the flywheel. While they look similar, they are not interchangeable—the reference sensor has a different wiring harness length and connector orientation on some models.

Part Number Variations by Model Year

Porsche used different sensors as the 944 evolved. The part numbers changed with the introduction of motronic systems, engine upgrades, and flywheel design updates.

1983–1985 Early 944 (2.5L 8V)

These cars use the original Bosch sensors. The speed sensor part number is 944 606 103 00. The reference sensor part number is 944 606 104 00. Both are black, with a metal bracket and a two-pin connector. Some aftermarket brands like Febi and Beru offer replacements under the same numbers.

1985.5–1987 944 (2.5L 8V with updated flywheel)

Mid-1985 saw a change to a different flywheel with a new trigger pattern. The speed sensor changed to 944 606 105 00. The reference sensor changed to 944 606 106 00. These sensors have a slightly different connector orientation and are often labeled with a color code: speed sensor has a green dot, reference sensor a red dot. If you have an ’85.5, verify your production date (after January 1985) or check the original part number on the old sensor.

1988–1989 944 (2.7L from 1988, 2.5L in 1989? Actually 1988 got 2.7L in 944, but 944S still 2.5L 16V)

Actually, the 944 2.7L (code M44.07) used in 1988 and 1989 (non-turbo) uses the same sensors as the late 2.5L? I need to be accurate. The 2.7L 944 (1988-1989) uses the same part numbers as the 1985.5-1987 2.5L: speed sensor 944 606 105 00, reference sensor 944 606 106 00. The 944S (1987) and 944S2 (1989) have separate part numbers.

944S (1987) – 2.5L 16V

For the 944S (16-valve engine), the part numbers are: speed sensor 944 606 107 00 and reference sensor 944 606 108 00. These sensors have a different resistance value and are specific to the 16V DME.

944S2 (1989–1991) – 3.0L 16V

The 944S2 uses a different flywheel and sensor arrangement. Speed sensor: 944 606 109 00. Reference sensor: 944 606 110 00. These are unique to the 3.0L 16V and are not interchangeable with 8V sensors.

944 Turbo (1986–1988) and Turbo S (1988)

The 944 Turbo uses a different sensor due to the larger flywheel and turbo-specific DME. Speed sensor: 944 606 111 00. Reference sensor: 944 606 112 00. Note: early 1986 Turbo may have slightly different numbers; verify with your VIN. The Turbo S (1988) uses the same parts.

944 Turbo Cup (1988) and 944 Turbo S (1989)

These rare models may use the same sensors as the standard Turbo, but it's best to cross-reference.

How to Identify Which Sensor Is Which

When buying sensors, you need to distinguish between speed and reference. Physically, they look identical. However:

• The speed sensor (engine speed) has a shorter cable (about 12 inches) and is mounted on the driver side (left) of the bell housing.
• The reference sensor has a longer cable (about 24 inches) and is mounted on the passenger side (right) of the bell housing.
• Often, the reference sensor connector faces opposite direction.

Look for colored dots on the sensor body: green dot = speed, red dot = reference (for some later models). If no dots, measure the resistance with a multimeter. The speed sensor resistance should be approximately 600–800 ohms, the reference sensor approximately 1.1–1.3 k ohms (though this varies by model). Always confirm with a known good sensor if possible.

Where to Buy and What to Expect

While we cannot list specific retailers, you can buy these sensors from Porsche dealerships, specialty Porsche parts suppliers, or well-known auto parts stores that carry Bosch or OEM equivalents. Expect to pay between $50 and $120 per sensor, depending on brand and model. Aftermarket options from brands like Meyle, Febi, or Beck/Arnley are available but may not match the exact fit or reliability of Bosch. For critical engine management, OEM or Bosch-branded sensors are recommended.

Installation Tips

Replacing these sensors is straightforward but requires caution. The sensors are held by a single 10mm bolt and plug into the DME harness via a two-pin connector. Before removal, mark the cable routing and bolt position. Use anti-seize on the bolt to prevent corrosion. Ensure the trigger wheel on the flywheel is clean and free of debris. After installation, start the engine and check for proper operation. If the car misfires or fails to start, double-check the connector orientation and sensor placement.

Final Recommendation

For a 944 owner, the safest approach is to verify your existing sensor's part number before ordering. If the original part number is illegible, use the guide above based on your model year and engine. Always buy from a trusted supplier that offers a return policy. For most 8V models (1983-1988), the late ’85.5-1987 sensors (944 606 105 00 and 944 606 106 00) are the most common. For 16V and Turbo, stick to the specific numbers listed. Replacing both sensors at the same time is a good practice, as they have similar age and wear. Keep your old sensors as emergency spares if they still function. With the right part numbers, you can get your 944 running reliably again.