P1842 Transmission Transfer Case Rear Shaft Speed Sensor Circuit Failure

As a car expert, I understand how frustrating it can be when your vehicle starts acting up. One common issue that many drivers face is a P1842 Transmission Transfer Case Rear Shaft Speed Sensor Circuit Failure. This problem can cause your car to shift poorly or even stall, making it difficult to drive. Fortunately, with a little know-how and some basic tools, you can fix this issue yourself. In this article, I will provide you with step-by-step instructions and useful tips to help you get your car back on the road.

Step 1: Diagnose the Problem

Before you can fix the issue, you need to diagnose it. The P1842 code indicates that there is a problem with the transmission transfer case rear shaft speed sensor circuit. This sensor is responsible for monitoring the speed of the rear driveshaft and sending that information to the vehicle’s computer. When the sensor fails, it can cause the computer to think that the driveshaft is not moving, which can lead to shifting problems and other issues.

To diagnose the problem, you will need an OBD-II scanner. This tool can read the codes stored in your car’s computer and give you an idea of what is causing the issue. Once you have the code, you can start troubleshooting the problem.

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Step 2: Check the Wiring

One common cause of a P1842 code is a wiring issue. Over time, the wires that connect the sensor to the computer can become damaged or corroded, which can cause the sensor to fail. To check the wiring, you will need to locate the sensor and follow the wires back to the computer. Look for any signs of damage or corrosion, and make sure that all of the connections are secure.

If you find any issues with the wiring, you will need to repair or replace it. This may involve splicing in new wires or replacing the entire harness. Be sure to use the appropriate tools and techniques to ensure a secure connection.

Step 3: Replace the Sensor

If the wiring checks out, the next step is to replace the sensor itself. The sensor is typically located on the transfer case or rear differential, depending on the make and model of your vehicle. To replace the sensor, you will need to remove any components that are blocking access to it, such as the driveshaft or exhaust system.

Once you have access to the sensor, remove it from its mounting location and disconnect the wiring harness. Install the new sensor in its place, making sure that it is properly aligned and secured. Reconnect the wiring harness and any other components that you removed, and test the vehicle to make sure that the issue has been resolved.

Useful Tips

– Always disconnect the battery before working on any electrical components to avoid the risk of shock or damage to the vehicle’s computer.
– Use a torque wrench to tighten any bolts or nuts to the manufacturer’s specifications to avoid over-tightening or under-tightening.
– If you are unsure about any aspect of the repair, consult a professional mechanic or refer to the vehicle’s service manual for guidance.


A P1842 Transmission Transfer Case Rear Shaft Speed Sensor Circuit Failure can be a frustrating issue to deal with, but with the right tools and knowledge, you can fix it yourself. By following the steps outlined in this article and using the tips provided, you can get your car back on the road in no time.


1. Can I drive my car with a P1842 code?

It is not recommended to drive your car with a P1842 code, as it can cause shifting problems and other issues that can make it difficult to control the vehicle.

2. How much does it cost to fix a P1842 code?

The cost of fixing a P1842 code can vary depending on the make and model of your vehicle and the extent of the damage. In general, you can expect to pay anywhere from $100 to $500 for parts and labor.

3. How long does it take to fix a P1842 code?

The time it takes to fix a P1842 code can vary depending on the complexity of the repair and the availability of parts. In general, you can expect the repair to take anywhere from a few hours to a full day.