Transmission Range Sensor Circuit Low Input
The transmission range sensor tells your engine computer what gear you've selected, but it's sending a voltage signal that's too low to read properly. Think of it like a dimmer switch stuck on the dimmest setting when it should be bright.
The ECU monitors the transmission range sensor voltage to identify selected gear position (Park, Reverse, Neutral, Drive). The sensor produces a variable voltage output based on selector position. When voltage falls below the minimum threshold, the ECU cannot reliably determine gear selection and triggers a fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 0.5V - 4.5V (varies by position) | Below 0.2V or open circuit |
| Signal Integrity | Stable voltage matching gear position | Erratic or continuously low signal |
Code P0708 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0708 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.