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P0709 is a diagnostic trouble code (DTC) for "Transmission Range Sensor Circuit Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0709 code is known as Transmission Range Sensor Circuit Intermittent.
The meaning of P0709 varies slightly among makes and models, but in general, this code indicates that the PCM (powertrain control module) has detected an issue in the shifting mechanism of the vehicle. This means that if the transmission range sensor can’t tell which gear you put the vehicle into, the PCM cannot tell the engine what to do as far as RPMs, fuel delivery, timing, and other actions. When the shifter indicates that you’re in Drive, for example, but the sensor tells the PCM you’re in park, the information being received from the speed sensor, transmission shift solenoids, torque converter lock-up solenoid, and various other sensors will not match with what’s actually happening.
The most common cause of this fault is a maladjusted transmission range sensor. This often results from transmission repairs after which the transmission range sensor is not adjusted properly. Other potential causes include a bad range sensor, a faulty park/neutral switch, or shorted or damaged wiring or connectors.
Symptoms of a transmission range sensor problem could include failure to shift, rough shifting, decreased fuel economy, a Check Engine Light, and the stored code.
Diagnosing this issue requires access to the appropriate wiring schematic for the vehicle. The arrangement of the transmission range sensor and its involved components varies among vehicles so it’s necessary to know exactly where to look in order to address the problem.
A mechanic will first check the stored codes using an OBD-II scanner, along with verifying whether there are any concurrent codes present. Each one should be diagnosed and repaired in the order in which it happened. The codes will then be cleared, and the vehicle retested to make sure the code returns.
The inspection should begin with a visual inspection of the PCM wiring and connectors. Any corroded, damaged, or shorted components should be replaced, and the system retested to see if the code comes back.
The range sensor diagram will be used to locate the associated parts and check the circuits for resistance and continuity using an ohmmeter.
It’s common for this problem to automatically be attributed to the transmission range sensor, when frequently all that’s needed is for the sensor to be readjusted.
Transmission problems can have catastrophic effects on a vehicle’s mechanical health. If the problem is producing harsh or absent shifting, further damage may be caused to the transmission, which requires very expensive and involved repairs.
Repairing this code may involve one or more of the following:
Due to the seriousness of the potential damage a transmission miscommunication can cause, this code should be addressed as soon as possible if detected in your vehicle. The wiring schematics for the park/neutral switch and transmission range sensor vary among vehicles, so it’s a good idea to have this problem assessed by a professional who will have access to the proper documentation.
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