Error Code P0709 code is defined as Transmission Range Sensor Circuit Intermittent. This is a generic trouble code, meaning it applies to all vehicles equipped with the 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 model to another.
Generally, Error Code P0709 slightly differs from one make and/or model to another. This means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has determined a problem in the shifting mechanism of the vehicle.
If the transmission range sensor can’t tell which gear the vehicle is into, then it will be unable to tell the engine what to do as far as fuel delivery, RPM, timing, and other actions. When the shifter shows the vehicle in Drive, for example, the sensor will tell the PCM that the vehicle is in Park. The information received from the speed sensor, torque converter lock-up solenoid, transmission shift solenoids, and various other sensors will be unable to match what is actually happening.
Other related transmission range sensor error codes include:
- Hard shifting or transmission unable to shift at all
- Increased fuel consumption
Other transmission range sensor related codes may be present as well.
- Misadjusted transmission range sensor
- Misadjusted transmission (shift cable/linkage)
- Bad range sensor
- Defective park/neutral switch
- Shorted or damaged wiring or connectors
How to Check
As with most codes, diagnosing this error codes requires access to the right wiring schematic for the vehicle. Transmission range sensor’s arrangement and other involved components varies from one vehicle to another, thus it’s important to know where to look on order to address the problem.
First, scan the stored codes using the OBD-II scanner and verify whether there are any concurrent codes present. Each should be diagnosed and repaired in the order in which it happened. Clear the codes and then take the vehicle for a test drive to find out if it returns.
Check the PCM wiring and connectors. Any damages, such as corroded or shorted components must be replaced. Retest the system to check if the code comes back.
Use the range sensor diagram to find the associated parts, use the ohmmeter to check the circuits for resistance and continuity.
How to Fix
Depending on the diagnosis, repairs for this code include:
- Readjustment of transmission range sensor
- Replacement of PCM connectors and wirings
- Replacement of transmission range sensor connectors and wiring
Problems in the transmissions range sensor can cause catastrophic issues to the vehicle. If the problem is causing absent or harsh shifting, it can further damage the transmission, which can be extremely expensive. Thus, it’s important to address this code as soon as possible.
The most common mistake in diagnosing this code is automatically attributing it to transmission range sensor when, in many cases, the sensor only needs readjustment.