P0717: Input/Turbine Speed Sensor 'A' No Signal

Quick answer

• What the P0717 code means: The P0717 code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) is not receiving a signal from the input/turbine speed sensor A.
• Severity: Get towed or have the vehicle inspected immediately. Driving with this code can cause significant transmission damage.
• Most common cause: A faulty input/turbine speed sensor.

What the P0717 code means

The P0717 diagnostic trouble code stands for "Input/Turbine Speed Sensor 'A' No Signal." This code is set when the vehicle's computer (either the PCM or TCM, depending on the vehicle manufacturer and transmission type) detects that there is no electrical signal or an intermittent signal from the input/turbine speed sensor. This sensor is crucial for monitoring the rotational speed of the transmission's input shaft, which is directly related to the engine's output speed and how it affects the transmission.

In plain English, your car's computer isn't seeing any information from a sensor that tells it how fast the main shaft inside your transmission is spinning. This information is vital for the transmission to shift gears smoothly and efficiently. Without this signal, the transmission can become confused, leading to various shifting problems or even entering a "limp mode" to prevent further damage.

Common symptoms

• Check Engine Light illuminated
• Transmission shifting erratically or harshly
• Transmission slipping out of gear
• Transmission stuck in a single gear (limp mode)
• Reduced fuel economy
• Cruise control may not work
• Vehicle may not shift into higher gears at all
• Vehicle may not move from a stop (in severe cases)

Common causes

1. Faulty Input/Turbine Speed Sensor 'A': This is the most common culprit. The sensor itself can fail electronically or physically.
2. Damaged or corroded wiring/connector to the input/turbine speed sensor: Fraying, short circuits, or open circuits in the wiring harness can prevent the signal from reaching the PCM/TCM.
3. Internal transmission mechanical failure: While less common, severe internal transmission damage could prevent the input shaft from spinning correctly or damage the sensor mounting, leading to a "no signal" condition.
4. Faulty PCM/TCM: In rare cases, the control module itself might be at fault, unable to properly read the sensor signal.

How a technician diagnoses it

A professional technician will follow a systematic approach to diagnose a P0717 code:

1. Verify the complaint and perform a visual inspection: The technician will first confirm the symptoms and check for any obvious damage to the wiring or connectors related to the transmission speed sensors. They will look for frayed wires, loose connections, or signs of rodent damage.
2. Scan for DTCs and freeze-frame data: A scan tool will be used to confirm the P0717 code and check for any other related codes. Freeze-frame data will be analyzed to understand the engine and vehicle conditions when the code was set.
   • Good values: Input speed sensor readings should typically correlate with engine RPM, especially in lower gears, and change smoothly with vehicle speed.
   • Bad values: A constant 0 RPM reading from the input speed sensor, or erratic/intermittent readings, even when the engine is running and the vehicle is moving, indicates a problem.
3. Check live data from the input/turbine speed sensor: The technician will monitor the input/turbine speed sensor's live data using a scan tool while the vehicle is driven (if safe to do so) or while the wheels are rotating on a lift. A healthy sensor will show a smooth, varying signal as RPM and vehicle speed change. If the sensor shows no signal at all, or a flat-line reading, then the problem lies with the sensor or its circuit.
4. Perform electrical checks on the sensor circuit: Using a multimeter, the technician will check for proper voltage supply to the sensor, ground continuity, and the integrity of the signal wire. This involves checking for opens, shorts, or excessive resistance in the wiring between the sensor and the PCM/TCM.
   • Good values: Reference voltage (typically 5V or 12V) and ground continuity should be present at the sensor connector. Signal voltage will vary with sensor activity.
   • Bad values: No voltage, no ground, or a constantly high or low signal voltage on the signal wire.
5. Test the input/turbine speed sensor: If accessible, the sensor itself may be tested for resistance or signal generation (AC voltage) while rotated manually. Some sensors are magnetic pickups that generate an AC voltage as a gear tooth passes by.

Typical repair cost

• Input/Turbine Speed Sensor Replacement: Parts can range from $50 to $200. Labor typically runs from $150 to $400, depending on the vehicle and accessibility of the sensor. Total cost: $200 - $600.
• Wiring Repair: Depending on the extent of the damage, wiring repair can cost between $100 and $300 for labor, plus minimal parts cost.
• Transmission diagnostics and internal repair: This can be significantly more expensive, ranging from $500 to over $3000, depending on the nature of the internal transmission issue.

Can I keep driving with this code?

No. It is not recommended to keep driving with a P0717 code. This code indicates a critical issue with the transmission