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Error Code P0706 is defined as Transmission Range Sensor Circuit Range/Performance. This means the transmission range circuit is not communicating data properly to the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes).
This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting and repairs of course, vary from one make and/or model to another.
The Transmission Range Sensor is also sometimes called Park/Neutral switch or Safety switch. It communicates with the vehicle’s transmission control module and PCM, and is attached to the manual valve of transmission.
Transmission Range switch identifies whether the selector lever is in park or in neutral, and it sends the signal to the transmission control module. It does so to ensure the vehicle starts in park and neutral position and inform the PCM about the position of the gear shifter. The PCM sends voltage reference to the sensor, while the sensor sends a different voltage back to the PCM, depending on which gear shifter is in.
Error Code P0706 happens when transmission is not receiving clear data from the transmission range sensor, or the return voltage is not what it’s supposed to be. This usually happens when the vehicle is moving and the reads that the vehicle is traveling at a speed that doesn’t match the PCM’s reading for the current shift position, such as such as traveling at any speed when transmission reads and reports that it’s still in park or neutral position.
Related error codes include:
Error Code P0814: Transmission Range Display Circuit
As with other error codes, Error Code P0706 activates the check engine light. Other symptoms include:
- Decreased power in acceleration
- Poor shifting
- Increase in fuel consumption
- Inability to switch gears
- Vehicle may also go into “limp” mode
There are many factors that may cause this error code to arise, such as:
- Poor quality or dirty transmission fluid
- Defective or damaged park/neutral position switch
- Improperly adjusted park/neutral position switch
- Defective or damaged transmission range sensor
- Defective, shorted or damaged wiring to the transmission range sensor
- Faulty manual shift valve linkage
- Defective or damaged valve body
- Shorted or open park/neutral position switch harness
- Defective or damaged control cable
- Bad electrical connections to park/neutral switch circuit
- Defective PCM (rare)
How to Check
Technicians start their diagnosis of this error code by using OBD-II scanner and check for the stored trouble code.
Then, they proceed on visually checking the range sensor and wiring harness and look for any signs of damage.
Next, they inspect all the connectors and wires related to the transmission range sensor and the PCM for any signs of damage.
Then, they find out if the vehicle will start while in reverse shift position or drive shift position.
Then they clear the codes, and then take the vehicle for a test drive to see if the code comes back.
Lastly, they check for continuity and resistance in the circuits.
How to Fix
Depending on the diagnosis, there are multiple ways to repair this error code, such as:
- Flush and fill transmission fluid (if necessary)
- Repair or replace faulty or damaged connectors or wirings
- Check voltage levels of the battery
- Repair or replace defective or damaged connectors or circuits
- Repair or replace defective or damaged transmission range sensors
- Repair or replace defective or damaged PCM
- Clear all codes, test drive the vehicle, and then rescan the codes if they come back
Error Code P0706 will cause problems with the operation and transmission of the vehicle, and will force the vehicle to go into “limp” mode. Thus, this error code is considered serious, and it’s very important that it gets addressed as soon as possible.
Also, sometimes, the code can be a result of engine misfire or driveline problem. It pays to check for other codes that may be present before you start repairing or replacing parts unnecessarily, as they may be the ones causing the problem.