Infiniti G35 Transmission Speed Sensor Location

Where the sensors are on a G35

Rear-wheel-drive G35 sedans and coupes with the five-speed automatic use a transmission commonly identified as the RE5R05A. On these cars, the output speed sensor mounts in the transmission case toward the rear of the unit. Nissan service literature calls it the revolution sensor. You reach it from underneath the car. It is typically held by a single bolt, seals with an O-ring and has its own electrical connector. The input or turbine speed sensors are internal. You cannot see them from outside, and servicing them means removing the oil pan and working around the control valve area, which is a much bigger job.

Use this as general orientation, not a measured diagram. The sensor's exact position relative to the crossmember, exhaust, heat shields and harness routing can vary with model year, body style and drivetrain. Confirm it against the factory service information or a parts catalog matched to your VIN before you start removing components.

How the speed sensors work

Each transmission speed sensor reads a rotating toothed or slotted member and sends a pulsing signal to the transmission control module. The input sensor reports how fast the turbine side is turning, and the output sensor reports how fast the output shaft is turning. Comparing the two lets the module work out which gear is actually engaged and detect slipping. It also uses them to time upshifts, downshifts and torque converter lockup. If a signal drops out or becomes implausible, the module can set a fault and switch to a fail-safe strategy. The driver then notices harsh or delayed shifts, a lack of upshifts or the car holding one gear.

Vehicle speed information can be shared between control units, and the ABS system has its own wheel speed sensor at each corner. That is why a speedometer problem, a traction or ABS warning and a transmission complaint can show up together. In those cases, the specific sensor named in the stored fault tells you more than the symptom alone.

What changes the answer

Transmission type matters most. G35s were offered with the five-speed automatic and a six-speed manual. Manual cars have no automatic shift control or internal turbine sensors, and their speed signal arrangement differs. A sensor listed for the automatic will not apply to them. Identify the transmission by VIN or build information rather than by assumption, especially on a car with an unknown history.

Drivetrain and generation also change things. The all-wheel-drive G35x adds a transfer case behind the transmission, which changes the underbody layout and can make access more awkward. The G35 name covers the first-generation sedan and coupe and the redesigned sedan of the later model years. Connector styles, harness routing and part numbers may differ between them. A replacement sensor that looks identical is not necessarily a correct fit, so confirm fitment against your exact vehicle.

The diagnostic code points you to the right part. Under generic OBD-II definitions, P0720 relates to the output speed sensor circuit, P0715 to the input or turbine speed sensor circuit, and P0500 to vehicle speed sensing. Codes in the C range from the ABS system point to wheel speed sensors instead. Manufacturer descriptions can be more specific, so use a scan tool that reads the transmission and ABS modules, not just the engine module.

What the owner can do

Start by scanning every module that can store codes, and write down the codes and any freeze frame data before clearing anything. Then note the shift behavior pattern: • harsh or flared shifts; • no upshift past a certain gear; • a sudden limp mode; • a speedometer that drops to zero; Record whether it happens cold or hot, over bumps or at a particular speed. A fault that appears over rough pavement often points toward a wiring or connector issue rather than the sensor itself. If your scan tool shows live data, compare input and output speeds while driving. A signal that drops out while the car is clearly moving is a useful clue.

With the car safely supported on stands and the exhaust cool, inspect the output sensor connector and the nearby harness from below. Look for: • chafed or broken wires; • corrosion or fluid inside the connector; • a broken locking tab; • a connector that has worked loose; Also check the fluid level and condition using the specified procedure for your transmission, and confirm the fluid specification matches what the owner's manual calls for. Low, degraded or incorrect fluid can cause shift complaints that look like a sensor problem. Review the service history for recent fluid work or transmission repairs.

If the evidence points to the external output sensor, replacement is usually straightforward: 1) Disconnect the connector. 2) Remove the retaining fastener. 3) Ease the sensor out without prying against the case. Expect a small amount of fluid loss. 4) Fit a new O-ring lightly coated with clean transmission fluid. 5) Tighten the fastener to the specified torque and reconnect the connector. 6) Clear the codes, road test the car and recheck the fluid level by the correct procedure.

Limitations and next step

A speed sensor code or a shifting symptom does not prove the sensor has failed. Several other causes can produce the same result: • a damaged harness or poor connector contact; • a control module fault; • low fluid; • an internal mechanical problem; The internal turbine sensors are not an easy driveway job. Diagnosing them properly often calls for circuit testing with wiring diagrams and a meter, plus experience with this transmission.

For exact sensor position, fastener torque, fluid level procedure and fitment, use service information tied to your VIN. If the code returns after a correct replacement, the external sensor and connector check out, or the fault points to an internal sensor, have a transmission specialist or dealer test the circuit. They can also compare live speed data and explain your repair options before any parts are replaced.