2006 Chrysler 300 Transmission Speed Sensor Location
On a 2006 Chrysler 300, the location of the transmission speed sensors depends on which automatic transmission the car has. Cars with the 42RLE four-speed have input and output speed sensors mounted on the outside of the case, on the driver's side. Cars with the five-speed NAG1 automatic have their speed sensing built into the control assembly inside the transmission pan. Confirm which transmission you have before buying a sensor or getting under the car.
Where the sensors sit on each transmission
On the 42RLE four-speed, both speed sensors are threaded or fastened into the left (driver's) side of the transmission case and are reached from underneath the car. The input speed sensor is toward the front, closer to the bellhousing, and reads the speed of the input shaft driven by the torque converter. The output speed sensor is farther back toward the tailshaft and reads output shaft speed. Each sensor has its own electrical connector. The two can look alike, so identify them by position and wiring rather than assuming they are interchangeable.
The five-speed NAG1 has no separate external speed sensor you can unbolt from the case. Its speed sensors are part of the conductor plate assembly inside the transmission, so reaching them means draining the fluid, removing the pan and working on the internal electrohydraulic controls. Replacing a speed sensor on this unit is therefore a much larger job than on the four-speed.
Keep in mind that the speed shown on the instrument cluster on this platform generally comes from wheel speed information shared between control modules. A speedometer fault is not automatically a transmission sensor problem and needs its own diagnosis.
How the speed sensors work
Each speed sensor sits close to a rotating part that has teeth or slots. As those features pass the sensor tip, it produces a signal whose frequency rises with shaft speed. The transmission control module compares input speed with output speed to work out which gear ratio is actually engaged, confirm that a shift has completed, judge slip and control torque converter clutch apply. If the readings do not match a valid gear ratio, or a signal drops out, the module can store a fault and switch to a protective limp mode. In that mode the car typically holds a single gear and accelerates sluggishly.
Because the module relies on these signals for shift timing, a faulty sensor or circuit can cause harsh, delayed or erratic shifts, flare between gears, or a sudden drop into limp mode. The same shift behavior can also come from low or degraded fluid, wiring and connector damage, control module faults, or internal mechanical wear. A symptom on its own does not prove that a sensor has failed.
What changes the answer
The main variable is transmission type. In the 2006 lineup, V6 rear-wheel-drive cars commonly used the 42RLE four-speed. The 300C with the 5.7 HEMI, the SRT8 and all-wheel-drive versions commonly used the five-speed. Don't rely on trim name alone. Confirm by counting forward gears, checking the identification tag on the transmission case, or having a dealer parts counter decode the VIN. If the service history shows the transmission was ever replaced, verify the unit actually installed rather than the original build.
Parts fitment matters even within the four-speed. Input and output sensors may carry different part numbers, and listings can vary by engine, drivetrain and production date. The surest match is the number printed on the sensor you remove, or a VIN-based lookup. Matching on model year alone is less reliable.
What the owner can do
Start with diagnostic codes, using a scan tool that can read the transmission module as well as the engine module. Under generic definitions, P0715 points to the input or turbine speed sensor circuit and P0720 to the output speed sensor circuit, and manufacturer-specific codes may add detail. A circuit code means the module saw an implausible or missing signal. It does not prove the sensor itself is bad. Write down the codes, any freeze frame data, and when the shift behavior changes, such as cold versus warm or at a particular speed.
Check fluid level and condition using the correct procedure and fluid specification for your transmission. The four-speed uses a dipstick and Chrysler specified ATF+4. The five-speed does not use a conventional owner dipstick check, and its level procedure differs. Low or burnt fluid changes the diagnosis and should be addressed before replacing parts.
On a four-speed car, with the vehicle safely supported, inspect each sensor connector and its wiring for oil soaking, corrosion, loose locks, chafing and heat damage. If you replace a sensor, clean around it first, expect a small amount of fluid to escape, fit any seal supplied with the new part, and recheck the fluid level afterward. Clear the codes and road test. If the same code returns with a new sensor installed, the wiring, connector or control module needs testing.
Limitations and next step
This guide describes general locations and logic. It does not give exact fastener sizes, torque values, connector pinouts or electrical test specifications, all of which should come from factory service information for your VIN. Circuit testing often calls for a multimeter or oscilloscope and wiring diagrams to tell a dead sensor from an open wire or a module problem.
Repair options range from a straightforward external sensor swap on the four-speed to internal conductor plate work on the five-speed, which may also need adaptation or setup steps afterward. If the car stays in limp mode, slips, smells burnt, leaks fluid, or keeps setting codes after a sensor replacement, have a transmission specialist confirm the cause before spending more on parts.