2013 Nissan Sentra Transmission Speed Sensor Location

Where the speed sensors are on a 2013 Sentra

On a CVT-equipped 2013 Sentra, the transmission speed sensors mount on the outside of the transaxle housing. The transaxle sits on the driver's side of the engine bay, bolted to the end of the 1.8-liter engine. Each sensor is normally held in by a single bolt and has its own electrical connector. The input sensor, which Nissan calls the primary speed sensor, reads rotation on the input or primary pulley side. The output sensor, called the secondary speed sensor, reads rotation on the output or secondary pulley side. To reach them you usually work from above after moving the air intake ducting, and sometimes the battery and its tray. Some steps are easier from underneath with the car safely supported on stands. The exact position on the case and the access steps should be confirmed in factory service information for your VIN.

Knowing which sensor you need matters more than knowing the general location. The generic code P0715 points to the input or turbine speed sensor circuit. P0720 points to the output speed sensor circuit. A scan tool that reads Nissan transmission codes and freeze-frame data can narrow the fault further than a basic engine-code reader.

How the transmission uses speed signals

The transmission control unit compares input speed with output speed to calculate the actual pulley ratio. It uses that figure to control hydraulic pressure, ratio changes and torque converter lockup. If one signal drops out or does not make sense compared with the others, the controller cannot confirm what the transmission is doing. It may then store a code, turn on the warning light and enter a fail-safe mode that limits acceleration or holds a fixed ratio range. Owners often describe this as the car feeling weak, revving without much speed, or refusing to accelerate normally.

These sensors read a toothed rotor or gear as it passes the sensor tip. A bad signal can come from the sensor itself, a corroded or loose connector, damaged wiring, metallic debris on the sensor tip, or the control unit. It can also come from a real mechanical problem. If the belt or pulleys slip internally, the sensors may report a genuine speed mismatch. In that case the sensor is working correctly, and the trouble lies inside the transmission. A speed sensor code is a starting point for diagnosis, not proof that the sensor has failed.

What changes the answer

Transmission type comes first. The 2013 Sentra was sold mainly with a CVT, and a six-speed manual was offered on the base trim. A manual-transmission car does not have the CVT's primary and secondary speed sensors. On many Nissans of this era, the speed shown on the gauge is calculated from the ABS wheel speed sensors and shared over the vehicle network. A parts listing labeled speed sensor may therefore be a wheel speed sensor rather than a transmission part. Check the transmission type on your vehicle information label or registration paperwork, or by decoding the VIN, before buying anything.

Model year boundaries also matter. The 2013 model year began a new Sentra generation, so parts and instructions for 2012 and earlier Sentras use a different transmission and do not apply. Fitment should be confirmed by VIN, because sensors for related CVT families can look alike but differ in connector style, length or part number. Operating conditions affect the diagnosis as well. Faults that appear only when the transmission is hot, after rain, or over rough roads usually point to wiring or connector problems rather than a sensor that has failed outright.

What the owner can do

Start by reading codes with a scan tool that can access the transmission module, not just generic engine codes. Write down every code and its freeze-frame data before clearing anything. If your tool shows live data, compare input speed, output speed and vehicle speed during a careful test drive or on a lift. A sensor that drops to zero, reads erratically, or disagrees with the others while the vehicle is moving steadily is a stronger lead than a code alone.

Next, inspect the connector and harness at the sensor you suspect. Look for corrosion, bent or pushed-back pins, oil contamination and chafed wiring near brackets. Check the fluid condition and service history as well. The CVT requires Nissan's specified CVT fluid, and the wrong fluid or an incorrect level can affect operation. This transmission may not have a simple owner dipstick. Level checks typically follow a temperature-controlled procedure, so if the service records are unclear, have a shop that follows the factory procedure verify the level.

If the evidence points to the sensor, replacement is usually simple. Disconnect the battery, unplug the connector, remove the bolt and pull the sensor straight out. Expect a small amount of fluid to seep out. Fit the correct new sensor with a new O-ring if one is supplied, and tighten the bolt to the factory specification. Then clear the codes and road test the car while watching live data to confirm that the signal is stable.

Limitations and next step

The locations described here are general. Exact sensor placement, access steps, torque values and wiring diagrams should come from factory service information matched to your VIN. If a code returns after a new sensor is fitted, if several transmission codes appear together, or if the car shudders, whines or slips, the problem may be internal. Have a transmission specialist diagnose it before you spend more on parts.

Depending on what the diagnosis finds, repair options range from a wiring or connector repair, a sensor replacement, a fluid service or a software update to a transmission repair or replacement. Before paying for major work, ask a Nissan dealer whether any warranty extension, recall or technical service bulletin applies to your VIN. Bring your recorded codes and service history, since these help the shop separate a simple sensor fault from a larger transmission problem.