Dealing with transmission issues is never fun, especially considering how complicated modern automatic transmissions are. That being said, most cars made in the last few decades feature a bunch of sensors that will help you figure out what’s wrong with them.

A malfunction in the transmission often triggers the check engine light code, which in turn illuminates the indicator on your dash. One of the errors you might run into is the P0706 code. Join us as we go over this particular error, what it means, its symptoms and causes, and how to diagnose it by yourself.

What is the P0706 Code, and What Does It Mean?

The P0706 DTC description reads “Transmission range sensor circuit range & performance”. Your transmission range sensor is an input sensor that communicates the current gear selection to the powertrain control module (PCM). This sensor in particular communicates whether the car is in park or neutral so that the vehicle only starts in those gears.

A P0706 code shows a failure somewhere in this system, either with the sensor itself or elsewhere along the circuit.

What Causes a P0706 Fault Code? 

Multiple causes can lead to this code, making it a challenge to diagnose. However, there are some of the most common ones:

• Transmission range sensor failure
• Bad relay
• Wire damage
• Powertrain Control module failure
• Internal transmission issues

Faulty Transmission Range Sensor

A faulty transmission range sensor is usually the main reason for the P0706 error. This sensor is often located somewhere on the side of the transmission, or near the valve body. More often than not, it’s mounted on the outside making it vulnerable to damage from stones or any dirt that skips up from the road surface. The motion of the vehicle can also cause it to come loose over time and malfunction. 

Once the sensor fails, your transmission won’t know when the car is in neutral and when it’s in gear. As a result, you’ll get that CEL on your dash which will most likely reveal the P0706 logged as a current DTC. 

Wiring Damage

If there is a break anywhere in the circuit, the voltage cannot travel to and from the sensor, Additionally, The wiring harness and wires themselves are protected by a rubber coating. Unfortunately, this protective coating tends to go brittle over time, especially if it’s exposed to endless series of hot/cold cycles. Any wires that are exposed can result in the trouble code.

PCM Failure

Although it is rare, the powertrain module uses the input from the sensor, so if it fails, it can cause a P0706 trouble code. A bad PCM often tends to be a factory defect, rather than something that happens over time, but a faulty battery or another electrical issue can cause it.

Where Is the Transmission Range Sensor Located?

You’ll find the transmission range sensor near the gearbox or the transmission valve body. The actual location of this unit depends on your car’s make and model. The best way to go about locating the TRS is to check your car’s service manual. That will remove a lot of the guesswork from the equation. 

Can Bad Transmission Fluid Cause P0706?

This issue involves the valve body. The valve body diverts hydraulic transmission fluid to change gears. If this fluid is not doing its job, this code can come up. Mainly because your car will not be able to change gears correctly.

What Are the Common Symptoms of P0706 Fault Code?

While there are many symptoms of this problem, most of them are pretty obvious right off the bat. Almost all these symptoms are serious as the transmission range sensor dictates whether you can slip the car in or out of gear. 

• The transmission is stuck in park 
• Inability to shift
• Check engine light
• Rough shifting
• Limp mode

Check Engine Light

To say a check engine light can mean anything is an understatement. Many modern vehicles will display a message that is more clear using the dash screen.

Despite this, it’s still the most important indicator that something is wrong with your car. A P0706 code will often cause a blinking engine light as it can be an immediate issue, but some vehicles will just illuminate it.

Limp Mode

Limp mode is a common feature in modern vehicles. It essentially prevents the car from damaging itself in situations like the one caused by the P0706 code. The car will no longer allow you to change out of the low gears or will reduce the power of the vehicle. 

Limp mode is almost always followed by a check engine light, so make sure to get the car inspected sooner rather than later. Sometimes the issue behind the limp mode can be quite severe. 

Transmission Issues

A malfunctioning transmission doesn’t necessarily mean dead transmission. You may still be able to drive without the vehicle shutting down, as a wiring issue might cause power to cut off intermittently or force the car into limp mode. This can cause other issues like sticky shifts, the car not being able to shift, or being stuck in park while driving.

You can already imagine that it’s dangerous to drive in those conditions. Not only can it damage your transmission or engine, but you could end up stuck in a situation with a vehicle that won’t come out of gear.

How to Diagnose the Cause of P0706 Code

There are several ways you can diagnose the cause of the P070 code. Fortunately for most car owners with this issue, the transmission range sensor is mounted on the outside of the transmission, which usually means that you can inspect it given that you have the right facilities to do so. If that yields no clues, there are a few other things you can try. 

Inspect the Vehicle

Inspecting your vehicle is an easy way to tell if there is any external damage to the wiring, PCM, or anywhere else along the transmission range sensor circuit. This becomes even more vital if your vehicle has been in an accident before, as this can sometimes indicate prior damage that may have contributed to your current car problems.

A break in the wiring harness, sensor, or major damage to the transmission body is a cause for concern and can trigger the P0706 code. Although it is rare, damage to the PCM can also lead to this trouble code, and it is worth checking.

Gear Testing

This issue involves external input from the gear lever. An easy way to test whether this is functioning properly is by starting your car in a gear that is not in park or neutral. The transmission range sensor is meant to prevent this.

Aside from just not engaging gears, erratic gear changes can also be an indicator of this trouble code. Shift through the gears, making sure to check whether the gears are actually changing in your vehicle.

Now, the indicator lights might move from P/N to D when you shift gears, but your car might not be shifting gears. This method is the first step in diagnosing a P0706 issue, although it is not the most conclusive, as the indicator lights can be fairly erratic.

It’s unsafe to run the vehicle at this point, and usually, a mechanic would use a dyno to test your car while shifting in this particular situation.

Relay Failure

A relay is a switch that opens and closes a circuit using electricity from the battery. Relay switch failure is a common issue related to the P0706 code, so much so that many mechanics will recommend inspecting/replacing it before the sensor.

Now, of course, you can replace the whole fuse box, but that is not the best option. Diagnosing each fuse might take longer and is a tedious process, so we recommend you consult your fuse and relay diagram for this one.

Once you’ve identified the correct relays, it’s time to reach for your multimeter. Set your multimeter to Ohms and touch the coil pins using the probes. Relay resistance differs depending on the manufacturers, but you should get between 50 and 120 ohms.

When testing the switch pins, your multimeter should read open when the car is in reverse, drive or low and voltage should be flowing through. You can also test this using your ODB II reader, which is more conclusive than a multimeter in this case.

Testing the PCM is a similar process. Voltage should only travel when the switches are open. Use your multimeter probes to contact the PCM wire inputs and your diagram to identify where the transmission range sensor wire comes into the module. 

Turn your car on. Shift through the gears. Similar to the switch pins, you should only receive voltage in drive, reverse, or low. If there is no voltage, you have a circuit issue, but if there is and the code is still present, you could have a faulty control module.

Wiring Damage

You’ll usually see a wire short when inspecting the harness, but sometimes the damage is internal. To diagnose internal wire damage, you need a multimeter.

You should always consult the wiring diagram before probing with your multimeter, as it makes it easier and quicker to diagnose the issue.

Testing for ground is the easiest way to tell if there is a short in the circuit. Your positive probe should be on the wiring harness pins and the negative probe should be touching a ground. The ground can be any metal part of your vehicle’s body. Turn your vehicle on. Any major drops in voltage or fluctuations will indicate that there is an issue with the ground wire.

How to Fix P0706 Code

Fixing the P0706 code might require you to pull out the parts cannon, but it’s not always necessary. In some cases, you could potentially fix this issue by doing something as simple as changing your transmission fluid. 

Transmission Fluid Change

Since dirty transmission fluid can cause the trouble code, it only makes sense to change it before replacing anything more expensive. Furthermore, it can help to flush the transmission to remove any dirt that may have accumulated. Do this even if you’re following a strict transmission maintenance schedule. It won’t cost you much, and you can get this done in your driveway. 

Component Replacement

A faulty battery is worth checking when you encounter any electrical issue. Cars use a 12V electrical system, so your battery should output around that amount when the car is on, and slightly more when you start your vehicle. Low voltage from the battery likely means that you need to replace it, which can resolve a P0706 code.

Replacing the transmission sensor and wiring is the more obvious solution to a P0706 code. Although sometimes this does require transmission removal, so it shouldn’t be your first thought.

If all else fails, you can attempt to replace the valve body or PCM. Unfortunately, these are expensive labor-intensive repairs. Luckily, it’s unlikely that these parts have failed, as they are considered low failure systems. The only way they fail is because of mechanical damage in an accident or skipping transmission fluid services and the PCM can fail in the event of a massive electrical short.

Does P0706 Clear Itself?

Although it can clear itself during a few driving cycles, for many reasons, it’s better to avoid driving your car until the issue has been addressed. Once you do so, It’s recommended that you clear the codes using an ODB II reader and then start the car to see if the codes remain.

Can You Drive with P0706 Code?

It’s a safety hazard to drive with this trouble code, mainly because your car may shift in and out of park or neutral while driving, and you will have no control over the car in such a situation. Unintended acceleration can also occur, and to avoid that, do not drive your vehicle.

Get Quality Parts For Your Car

Diagnosing a P0706 Code can be tedious. So many things can go wrong that it’s easy to be dissuaded from solving the issue. However, it can be done, and any car owner can do it.

A transmission issue can be a pain to deal with. Luckily, our website is not. Here at eEuroparts.com, you can use our simple interface to select your car and choose from a wide range of parts that fit your vehicle.