What happens when a transmission range sensor fails?

A faulty transmission range switch can cause several problems, the most common being the transmission getting stuck in gear (limp mode) and not changing gears.

In some cases, the engine may not start because the Powertrain Control Module (PCM) can not determine if the gear selector (shifter) is in Park. The shifter needs to be in Park to start the engine.

Table of Contents

The transmission range sensor on an Audi or Volkswagen may also be referred to as a multi-function switch, F125, neutral safety switch, position sensor, safety switch, or range sensor.

Causes

Problems related to the Volkswagen transmission range sensor include:

• The range sensor itself can fail
• Corrosion at connector
• Damaged wire harness from ECU / TCM to transmission
• Defective or damaged park/neutral position switch
• Improperly adjusted park/neutral position switch.
• Defective, shorted, or damaged wiring to the transmission range sensor
• Misaligned shifter linkage
• Misadjusted park/neutral position switch
• Park/neutral position switch harness is open or shorted
• Park/neutral position switch circuit has a poor electrical connection

Even though the transmission range sensor on a Volkswagen often fails, as you can see, the problem may not always be the transmission range sensor itself.

In some cases, even low transmission fluid levels can develop similar symptoms, such as transmission not shifting gears or limp (failsafe) mode.

Symptoms

Volkswagen transmission range sensor can fail and cause several problems, including limp mode, no gear, or bang when putting the transmission in gear.

VW transmission range sensor problems are often caused by worn-out contacts inside the transmission control sensor or corroded contacts at the plug that connects to the range sensor. Similar symptoms can also be caused by a bad Transmission Control Module (TCM); therefore, check the TCM for water damage and corrosion.

This is a list of possible symptoms caused by a faulty position sensor switch. Typically only one or two problems are present depending on how your sensor range sensor fails.

• Car won’t start
• Car won’t move in Drive
• Vehicle in limp or fail-safe mode
• No gear is shown on the cluster. The block of PRND letters highlighted
• Gearbox goes in limp mode when in Park
• The car starts only in Drive
• The car starts only in Neutral, not in Park
• Inability to switch gears
• Transmission in failsafe mode
• PRND does not show current gear
• The transmission gear indicator is not working, and the car won/t start

Some of these symptoms may also be caused by low transmission fluid level, faulty valve body, bad throttle/pedal sensor, misaligned shifter cable, input/output shaft sped sensors, or water damage transmission control module (TCM). It is important to read the fault codes from the transmission control and engine control modules with a Transmission OBD2 Scanner to narrow down the problem before replacing any parts.

Possible Codes

Common fault codes triggered by a faulty transmission range sensor are P0705 and P0706. These fault codes typically mean that the transmission range sensor does not communicate data to the PCM (powertrain control module. Therefore the Engine Control Module does not know which gear the transmission is in or which gear the driver has selected.

• P0706 / 17090 – Transmission range sensor A, circuit range performance.
• 00293 VW Code – Multi-Function Switch (F125): Implausible SignalOn 5-Speed Automatic Transmission (01V)
• 17091 – Transmission Range Sensor (F125): Signal Too Low
• 17090 – transmission range sensor F125, implausible signal
• P0707: Transmission Range Sensor Circuit Low Input
• 01119 – Gear Recognition Signal
• P0814: Transmission Range Display Circuit
• P0708: Transmission Range Sensor Circuit High Input
• P0709: Transmission Range Sensor Circuit Intermittent
• P0819: Up and Down Shift Switch to Transmission Range Correlation
• 00293 Multi-function Switch (F125) Undefined switch condition error
• U102600 Transmission Control Module Read Out DTC
• P0919 Gear shifter position control error
• P1624 Malfunction lamp on / check engine light on

P codes are generic fault codes. They often come up on VW cars such as Jetta, Bora, Golf, GLI, Beetle, CC, Rabit, Tiguan, Routan, and Passat, but they can come upon any car with a faulty automatic transmission range sensor.

Codes that start with a number are Volkswagen-specific codes.

In some cases, a faulty code that points to a faulty transmission range sensor may be caused by a faulty Transmission Control Module (TCM / TCU). On Volkswagens, the TCM is often mounted on the floor of the passenger footwell. Water can get to the TCM module and either damage or cause corrosion. Before you replace the range selector sensor, it is recommended to inspect the TCM for water damage and corrosion.

Troubleshooting Transmission Range Sensor Problems

Check Fluid Level

If you have problems with your VW transmission going in limp mode or fail-safe mode, you first need to check the transmission fluid level. Many of the symptoms you may think are caused by a faulty transmission range sensor can also be due to low transmission fluid levels.

Read Codes

Use a Volkswagen Audi OBD-II scanner to read fault codes from the engine control and transmission control modules. Pay attention to all codes that show as CURRENT / PRESENT or ACTIVE. These codes will tell you what is wrong with your VW.

Fault codes that show as PASSIVE can also give you a hint, but don’t worry too much about passive codes until you fix the ACTIVE codes first. Fix the ACTIVE codes, then address the PASSIVE codes if they return.

Remember that generic OBD-II scanners will read engine control module codes but can not read codes from the transmission control module. If your check engine light is not on, a generic OBD-II scanner may not show any codes, even if fault codes exist in the transmission control module.

Check voltage

Next, use a digital multimeter to check the battery and alternator voltage. If your VW has a below 12 volts voltage with the engine running, you may have an electrical problem putting the transmission in limp mode.

Transmission range sensor connector

The next step is to check the connector that goes to the transmission range sensor. The connector can be loose or corroded, causing communication problems between the transmission range sensor and PCM.

Check TCM

Next, check the Transmission Control Module (TCM) for water damage. The TCM is mounted in the passenger footwell on some VW models, and water can potentially get to the module and destroy it.

Once you have checked the basics and ensured there is no corrosion or water damage, replace the transmission range sensor. The transmission range switch is also called a neutral safety switch because it prevents the engine start if the transmission is NOT in the park and neutral position. The PCM sends voltage reference to the sensor, while the sensor sends a different voltage back to the PCM, depending on which gear the shifter is in.

Since VW and Audi share many parts, including transmissions, these steps and problems apply to many Audi vehicles.

This guide covered problems with transmission range season on Volkwagen, but since the same symptoms, causes and functions can be applied to other vehicles with automatic transmission such as Acura,  BMW, Honda, Hyundai, Mitsubishi, Mazda, Volvo, Ford, Dodge, GMC, Chevrolet, etc.

Where is the transmission range sensor located?

The transmission range sensor is typically mounted on the transmission housing. Depending on the model, the transmission range sensor will be mounted on top of the transmission or the side of it. The Volkswagen transmission range sensor serves many functions to determine the driver’s desired gear ( P R  N D ). The transmission range sensor sends the signal to the Powertrain Control Module (PCM).

Will a car start with a faulty transmission position sensor?

It depends on how and how the transmission range sensor fails. The transmission can go in limp mode, stop changing gears, or the engine may not start at all. In addition to telling the transmission control unit which gear the driver has selected ( P R N D), the transmission range sensor also performs a critical function. It prevents the engine start if the shifter is not in Park or Neutral.

That’s why, in some cases, the vehicle will not even start if the transmission position sensor is faulty. If the engine control module (ECU) can not determine that the vehicle is not in Park ( or Neutral), it will not allow you to start the engine.

Can I drive with a bad transmission range sensor?

A faulty transmission range selector will cause problems such as forcing the car to get stuck in one gear or what is known as a limp mode. In other cases, it may prevent you from starting the engine. Problems with the transmission range sensor (neutral safety switch) should be repaired as soon as possible.

Which VW are affected by this problem?

Most vehicles with automatic transmissions have a transmission range sensor. This guide applied to most VW and Audi vehicles with automatic transmission, including the four-speed (01M) or five-speed (09A).

Resources

1. https://www.tasteslikepetrol.net/2019/11/vw-passat-transmission-range-switch-replacement/
2. https://www.2carpros.com/questions/transmission-range-sensor-88679113

We hope you find the Volkswagen Transmission Range Sensor | F125 guide helpful. Check these troubleshooting and repair guides for more help on your Volkswagen.

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