Porsche 928 Sensor Part Number 160.31 – Identification and Replacement Guide

The Porsche 928 is a classic grand tourer known for its advanced engineering, and part number 160.31 plays a crucial role in its engine management. This sensor is often a coolant temperature sensor used in the LH-Jetronic fuel injection system found on many 928 models. Understanding this part, its function, failure symptoms, and replacement procedure is key to keeping your 928 running smoothly. This guide provides practical, specific information to help you identify and replace sensor 160.31 without hype or unnecessary fluff.

What Is the Porsche 928 Sensor Part Number 160.31?

The part number 160.31 corresponds to a Bosch coolant temperature sensor (also known as a coolant temperature sender) used extensively in Porsche 928 vehicles with LH-Jetronic fuel injection. This sensor measures the engine coolant temperature and sends that information to the engine control unit (ECU). The ECU uses the temperature reading to adjust fuel mixture, ignition timing, and idle speed during warm-up and normal operation. A properly functioning sensor ensures optimal cold starts, smooth idle, and efficient fuel consumption.

How It Works

The 160.31 sensor is a negative temperature coefficient (NTC) thermistor. As coolant temperature increases, its electrical resistance decreases. The ECU reads this resistance change and calculates the corresponding temperature. Based on that value, the ECU modifies injector pulse width and other parameters. For example, when the engine is cold, the sensor reads high resistance (low temperature), prompting the ECU to enrich the fuel mixture for easier starting. As the engine warms, resistance drops, and the ECU leans out the mixture.

Which Porsche 928 Models Use This Sensor?

The 160.31 sensor is primarily associated with 928 models equipped with the LH-Jetronic fuel injection system. This includes:

• Porsche 928S (1980–1986) – Many 928S models, especially those produced after 1980, used LH-Jetronic and therefore the 160.31 sensor.
• Porsche 928S4 (1987–1991) – The S4 models retained LH-Jetronic and typically use this sensor.
• Porsche 928 GTS (1992–1995) – The GTS also uses a similar coolant temperature sensor, though it may be part of a later revision; the 160.31 still fits most GTS engines.

It is important to confirm your specific model year and engine type. The sensor is typically located on the intake manifold near the thermostat housing or on the coolant crossover pipe. For early 928 models (1978–1979) with K-Jetronic, a different sensor (e.g., 160.03 or 160.08) is used. If in doubt, check your existing part or consult a Porsche parts specialist.

Symptoms of a Failing 160.31 Sensor

When the coolant temperature sensor deteriorates, it can cause a variety of driveability issues. Common symptoms include:

• Hard starting when cold or hot – A faulty sensor may send an incorrect temperature signal, causing the ECU to provide too much or too little fuel.
• Rough idle or stalling – The ECU may struggle to maintain a stable idle if the temperature reading is erratic.
• Poor fuel economy – An inaccurate cold reading can keep the engine in warm-up enrichment too long, wasting fuel.
• Hesitation or surging during acceleration – Incorrect fuel mixture due to a bad sensor can cause lean or rich conditions.
• Check engine light (CEL) – The ECU may store a fault code for coolant temperature sensor range/performance (e.g., code 12 on many 928 ECUs).

These symptoms can also be caused by other issues (vacuum leaks, faulty oxygen sensor), so proper diagnosis is recommended.

Testing the Sensor

Before replacing the sensor, you can test it with a digital multimeter to confirm it is out of specification.

1. Disconnect the sensor’s electrical connector.
2. Set your multimeter to measure resistance (ohms).
3. Measure between the two terminals of the sensor (or one terminal and ground for a single-wire sensor; the 160.31 is typically two-wire).
4. Compare the reading to factory specifications:
   • At 20°C (68°F): approximately 2.5 kΩ.
   • At 80°C (176°F): approximately 300 Ω.
   • At 100°C (212°F): approximately 185 Ω.

If the resistance is significantly different or open (infinite), replace the sensor. You can also test the sensor’s response by heating it in a pan of water (carefully) and checking resistance as temperature changes.

Replacement Procedure

Replacing the 160.31 sensor is a straightforward job for a DIYer with basic tools. Always allow the engine to cool completely before working.

1. Drain coolant – Drain enough coolant to lower the level below the sensor. On the 928, the sensor is often located on the intake manifold or crossover pipe. You may need to drain a gallon or more.
2. Remove electrical connector – Gently pull off the connector; it may have a locking tab.
3. Unscrew the sensor – Using a deep socket (usually 19mm or 22mm, depending on the version) or a wrench, carefully remove the sensor. Some coolant may spill.
4. Clean the mounting surface – Ensure the sealing surface is clean and free of old gasket material.
5. Install the new sensor – Apply a small amount of thread sealant (such as Loctite 565) to the threads of the new sensor to prevent leaks. Do not over-tighten; torque to approximately 18–22 Nm (13–16 lb-ft).
6. Reconnect the electrical connector – Ensure it clicks firmly into place.
7. Refill coolant – Use the correct Porsche-approved coolant mixture (typically G12 or G11). Bleed the cooling system if necessary.
8. Start the engine and check for leaks. Let the engine reach operating temperature and verify that the temperature gauge and ECU readings are normal.

Where to Find the Correct Part

To ensure proper fit and function, always purchase a sensor that matches the original Bosch part number 160.31. This part is manufactured by Bosch and is also sold under Porsche dealer part numbers (e.g., 928 606 216 00 or similar). Reliable sources include:

• Porsche dealerships – Genuine OEM parts available but often at a premium.
• Specialized Porsche parts suppliers – Companies like Pelican Parts, ECS Tuning, and others that stock Bosch and OEM quality components.
• Online Bosch distributors – Many Bosch-authorized retailers sell the 160.31 sensor.

Avoid low-cost, unbranded replacements. They may have incorrect resistance curves or poor build quality, leading to inaccurate readings and premature failure. The 160.31 sensor is widely available and typically costs between $30 and $60 for a quality Bosch unit.

Final Recommendation

For a dependable repair, replace your Porsche 928 coolant temperature sensor with a genuine Bosch 160.31 part. This sensor is essential for proper engine operation, and using a quality component ensures accurate temperature readings, smooth running, and long life. Before purchasing, verify the sensor part number on your existing unit or cross-reference your VIN with a reputable parts supplier. If you experience any of the symptoms mentioned, testing and replacing the sensor is a cost-effective first step in restoring driveability. With a careful replacement, your 928 will continue to deliver the grand touring experience it was designed for.

Note: Always consult your vehicle’s service manual for specific torque specs and procedures, as variations exist between model years.