Speed Sensor Replacement

My 911 could not start. Both alternator and fluid pump were working fine. Using the diagnostic method below I found out the resistances were zero. 911 3.2 engine requires both Speed and Reference sensors to work to start the engine.

Speed and Reference sensor connector locations and diagnostic method.

Sensor with harness part numbers. Other part numbers -91160621501

91160621500 - this is an old number
ref. 026121002 and cross reference 12141708619 m14

Sensor positions and gaps between the sensors and the crankshaft.

Pictures are showing speed sensor with harness going through the grommet between the engine bay and outside where the sensor location.

The grommet contains 3 wire harness which are speed, reference and temperature sensors.

Tool I used to remove the grommet.

The speed sensor in your 911 G-Model is a critical component that affects multiple systems within your vehicle. When the speed sensor malfunctions, it can lead to a range of issues, including starting problems. In this article, we will explore common symptoms that indicate a faulty speed sensor in your 911 G-Model, including erratic speedometer readings, ABS/Traction Control malfunctions, transmission problems, and failure to start. We will also provide solutions to address these issues effectively and restore optimal performance.

Erratic Speedometer Readings:

One of the primary indications of a malfunctioning speed sensor is an erratic speedometer. If your speedometer displays inconsistent readings, fluctuates rapidly, or fails to function altogether, it is likely due to a faulty speed sensor.

ABS/Traction Control Malfunction:

A malfunctioning speed sensor can also affect the proper operation of the ABS and traction control systems in your 911 G-Model. If you notice warning lights on your dashboard, such as the ABS or traction control light, or experience decreased braking efficiency or limited traction control engagement, it may indicate a problem with the speed sensor.

Transmission Problems:

The speed sensor is crucial for the smooth operation of the transmission in your 911 G-Model. A defective speed sensor can result in transmission-related issues such as harsh shifting, delayed gear changes, or even transmission failure. If you experience any of these symptoms, it is advisable to check the speed sensor.

Failure to Start:

In some cases, a malfunctioning speed sensor can prevent your 911 G-Model from starting. The engine control unit (ECU) relies on accurate speed data from the sensor to initiate the starting process. If the ECU does not receive the necessary speed signal, it may prevent the engine from starting.

A malfunctioning speed sensor in your 911 G-Model can lead to symptoms such as erratic speedometer readings, ABS/traction control malfunction, transmission problems, and failure to start. By recognizing these symptoms and taking appropriate action, such as replacing the speed sensor, you can restore optimal performance and resolve starting problems. Consult a qualified technician to diagnose the issue accurately and ensure a proper replacement if necessary. Enjoy a smoother and more reliable driving experience with a functioning speed sensor in your 911 G-Model.