P0708
Transmission Range Sensor Circuit High
If your vehicle's onboard computer has flagged the diagnostic trouble code P0708, it refers to a detected anomaly regarding "Transmission Range Sensor Circuit High". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
A P0708 fault code points directly to a problem with transmission range sensor circuit high that the ECM has confirmed over multiple drive cycles. Drivers typically experience check engine light, incorrect gear display on dashboard, limp mode when this code is active. This is a moderate-severity fault — plan a repair shop visit within the week to keep it from escalating.
Symptoms
Check engine light, incorrect gear display on dashboard, limp mode
Common Causes
- Short to battery voltage in TR sensor circuit
- Defective TR sensor
- Broken ground wire to the sensor
- Internal transmission wiring issue
How to Fix
- 1 Trace and repair short to voltage
- 2 Replace Transmission Range Sensor
- 3 Fix broken ground wire
- 4 Inspect internal transmission harness
Technical Explanation
Detection of P0708 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. Shift solenoid circuits are monitored for both functional performance (does the transmission achieve the commanded gear ratio?) and electrical integrity (is the solenoid's resistance within the normal range of 10–40 ohms?). The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
While the vehicle is typically drivable with P0708 active, avoid towing, aggressive acceleration, or extended highway driving until the fault is resolved. The primary risk is accelerated wear on short to battery voltage in tr sensor circuit and defective tr sensor.
Mechanic's Pro Tip
The most common mistake with P0708 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Sensor replacement: $150 - $400