Lexus GS300 Automatic Transmission Input Speed Sensor Guide (1993-1999)
Experiencing harsh shifting or a P0715 code on your first-generation GS300? Your input speed sensor may be the culprit.
- A faulty input speed sensor is a primary cause of harsh shifting and the P0715 trouble code on 1993-1999 GS300s.
- This is a DIY-friendly repair; the sensor is on the exterior of the transmission's driver side, held by one bolt.
- A quality aftermarket brand like Standard Ignition provides a reliable, cost-effective fix compared to the more expensive OEM part.
- Do not ignore this issue, as prolonged harsh shifting can cause additional stress and wear on the transmission.
Symptoms of a Failing Input Speed Sensor in a GS300
When the input speed sensor on your Lexus GS300 begins to fail, it sends incorrect or no data to the car's computer, leading to several noticeable transmission problems. Unlike a failing output speed sensor which typically affects the speedometer, a bad input sensor primarily impacts shift quality.
- Harsh or Erratic Shifting: This is the most common symptom. The transmission may slam into gear, hesitate, or shift at inappropriate times because it can't determine the correct shift points.
- Check Engine Light: A faulty input speed sensor will almost always trigger a Check Engine Light. The most common diagnostic trouble code (DTC) associated with this failure is P0715 (Input/Turbine Speed Sensor Circuit Malfunction).
- Transmission "Limp Mode": In some cases, the transmission may enter a fail-safe mode to prevent damage, locking itself into a single gear (often 2nd or 3rd).
- Failure of Cruise Control: The cruise control system relies on accurate speed data to function and will often become inoperative when this sensor fails.
Choosing the Right Aftermarket Part: OEM vs. Aftermarket
When replacing the input speed sensor, you have the choice between an original equipment (OEM) part from Lexus/Toyota and an aftermarket part. The OEM sensor for this GS300 is part number 89413-24010.
For a vehicle of this age, a high-quality aftermarket part offers a sensible balance of cost and reliability. Unlike more complex engine components, a speed sensor is a relatively simple magnetic pickup. Reputable aftermarket brands produce sensors that meet or exceed original specifications.
- OEM (Lexus/Toyota): Offers a guaranteed fit and the highest quality, but at a significantly higher price point.
- Standard Ignition (SMP): Standard is a well-regarded aftermarket manufacturer known for producing reliable electronic components that are designed to match OE fit and function. For this repair, a Standard Ignition sensor is a dependable and cost-effective solution.
Pro Tip: Check Both Sensors
Your GS300 transmission has both an input and an output speed sensor located on the driver's side of the transmission case. Given the vehicle's age, if one has failed, the other may not be far behind. Since they are located near each other and replaced using the same procedure, consider replacing both at the same time to save on future labor.
Cost to Replace the GS300 Input Speed Sensor
Replacing this sensor is more affordable than many other transmission repairs, especially if you do the work yourself. The part is externally mounted, making it accessible without removing the transmission.
| Part or Service | Estimated Cost |
|---|---|
| New OEM Part (Lexus) | $90 - $150 |
| New Aftermarket Part (Standard Ignition) | $68.52 |
| Shop Labor | $85 - $130 |
| Total Professional Replacement (Aftermarket) | $153 - $199 |
Frequently Asked Questions (FAQ)
Can I replace the GS300 input speed sensor myself?
Yes, this is a very DIY-friendly repair for someone with basic tools. The sensor is located on the driver's side of the transmission and is held in by a single 10mm or 12mm bolt. You will need to safely raise the vehicle on jack stands to access it from underneath. The process involves unplugging the connector, removing the bolt, and swapping the sensor.
Where is the input speed sensor located on the 1993-1999 GS300?
You will find two speed sensors on the driver's side of the transmission housing. The input speed sensor (also called the No. 1 sensor) is the one located further forward, closer to the engine/bell housing. The output sensor is closer to the rear, near the driveshaft.
What happens if I don't replace a bad input speed sensor?
Continuing to drive with a bad sensor will result in persistent harsh shifting, which puts unnecessary stress on the internal clutches and components of your transmission. This can accelerate wear and potentially lead to more severe and expensive transmission damage over time.
Are there any recalls for this sensor?
No, there are no specific recalls or technical service bulletins (TSBs) from Lexus or the NHTSA for the automatic transmission input speed sensor on the 1993-1999 GS300. Failures are generally due to the age and mileage of the vehicle.
Technical Specifications
OEM Part Numbers: 89413-24010
Externally mounted magnetic sensor with a single bolt mount and 2-pin electrical connector.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Lexus GS300: