The P0708 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the transmission range sensor circuit. This sensor, also known as the neutral safety switch, plays a crucial role in ensuring that the vehicle’s transmission operates correctly by sending signals to the engine control module (ECM) regarding the position of the gear shifter. When the ECM detects conflicting signals from this sensor, it triggers the P0708 code, which can lead to various transmission-related problems.
The P0708 code typically signifies that the transmission range sensor is reporting a high input signal, which may prevent the vehicle from starting or cause erratic shifting behavior. Understanding this code is essential for vehicle owners and DIY mechanics who wish to diagnose and repair transmission issues effectively.
| P0708 Code Meaning | P0708 Code Common Causes |
|---|---|
| Transmission Range Sensor Circuit High Input | Misadjusted or faulty transmission range sensor |
| Conflicting gear position signals detected by ECM | Damaged or corroded wiring and connectors |
| Transmission may enter limp mode | Faulty ECM (Engine Control Module) |
| Check Engine Light illumination | Improperly adjusted shift cable or linkage |
Symptoms of P0708 Code
When dealing with a P0708 code, vehicle owners may notice several symptoms that indicate a problem with the transmission range sensor circuit:
- Check Engine Light: The most immediate indication of a P0708 code is the illumination of the check engine light on the dashboard.
- Erratic Shifting: Drivers may experience unexpected shifts or harsh shifting between gears, which can lead to discomfort and reduced vehicle performance.
- Limp Mode: In some cases, the vehicle may enter limp mode, restricting it to one gear and limiting acceleration to prevent further damage.
- Starting Issues: The engine may fail to start if the transmission range sensor does not correctly report that the vehicle is in park or neutral.
- Loss of Engine Power: There may be noticeable drops in engine power during acceleration due to improper gear engagement.
Technical Explanation of P0708 Code
The P0708 code is classified as a type B DTC, meaning that the ECM must detect the same malfunction twice before activating the check engine light. This occurs when conflicting signals are received from the transmission range sensor for more than 30 seconds. The sensor itself monitors the position of the gear shifter and communicates this information to the ECM via voltage signals. If it detects two different gear positions at once, it triggers the P0708 code.
Step-by-Step Diagnosis
Diagnosing a P0708 code involves several systematic steps:
- Scan for Codes: Use an OBD-II scanner to confirm that P0708 is present and check for any additional codes that may provide further insight into related issues.
- Visual Inspection: Examine wiring and connectors associated with the transmission range sensor for signs of damage, corrosion, or disconnection.
- Test Transmission Range Sensor: Follow manufacturer-specific procedures to test the functionality of the transmission range sensor. This may involve checking its resistance and output signals while moving through different gear positions.
- Inspect Shift Cable/Linkage: Ensure that the shift cable or linkage is properly adjusted and functioning correctly. Misalignment can lead to incorrect readings from the transmission range sensor.
- Check ECM Functionality: If all other components appear functional, consider testing or replacing the ECM as it may be misinterpreting signals from the transmission range sensor.
Solution Methods
To resolve a P0708 trouble code, consider these potential solutions:
1. Adjusting or Replacing Transmission Range Sensor
- Symptoms: If erratic shifting occurs alongside a check engine light.
- Technical Explanation: Misadjustment of the transmission range sensor can lead to incorrect voltage signals being sent to the ECM.
- Step-by-Step Solution:
- Locate the sensor based on your vehicle’s service manual.
- Adjust its position according to specifications.
- If adjustment does not resolve issues, replace with a new sensor.
- Cost Estimate: Replacement sensors typically range from $50 to $150, plus labor costs if performed by a mechanic.
2. Repairing Wiring and Connectors
- Symptoms: Visual inspection reveals damaged wiring or corroded connectors.
- Technical Explanation: Damaged wiring can disrupt signal flow between components, leading to erroneous readings.
- Step-by-Step Solution:
- Inspect all wiring related to the transmission range sensor.
- Repair any damaged sections using electrical tape or soldering as necessary.
- Replace corroded connectors with new ones.
- Cost Estimate: Repair costs vary but expect around $20-$100 depending on parts needed and labor if outsourced.
3. Adjusting Shift Cable/Linkage
- Symptoms: Difficulty in shifting gears or unusual shifting patterns.
- Technical Explanation: A misaligned shift cable can prevent proper communication between the gear shifter and transmission components.
- Step-by-Step Solution:
- Check alignment according to manufacturer specifications.
- Make necessary adjustments to ensure proper alignment.
- Cost Estimate: Typically low-cost; adjustments can often be done without parts unless replacement cables are needed ($30-$100).
4. Replacing ECM
- Symptoms: All other components test functional but issues persist.
- Technical Explanation: A faulty ECM may misinterpret signals from various sensors, including those from the transmission range sensor.
- Step-by-Step Solution:
- Consult with a professional mechanic for testing.
- Replace with an OEM or compatible aftermarket ECM if determined faulty.
- Cost Estimate: ECM replacement can be expensive, ranging from $200 to $800 depending on vehicle make/model plus labor costs.
Warnings and Recommendations
When addressing a P0708 trouble code:
- Always consult your vehicle’s service manual for specific diagnostic procedures tailored to your make and model.
- If you are unsure about any step in diagnosing or repairing this issue, seek assistance from a qualified mechanic to avoid further complications.
- Regular maintenance of your vehicle’s transmission system can help prevent codes like P0708 from occurring in the future. This includes routine checks on fluid levels, filter replacements, and ensuring all electronic components are functioning properly.
Closing Paragraph
The P0708 trouble code indicates significant issues within your vehicle’s transmission range sensor circuit that require prompt attention. By understanding its symptoms, causes, and potential solutions, vehicle owners and DIY mechanics can effectively diagnose and resolve this issue before it leads to more severe transmission problems. Remember that while some repairs can be handled at home, consulting with professionals is advisable when in doubt about any aspect of diagnosis or repair.
Frequently Asked Questions About P0708
- What does P0708 mean?
The P0708 code indicates a problem with the transmission range sensor circuit high input. - What are common symptoms of P0708?
Symptoms include erratic shifting, check engine light illumination, limp mode activation, and starting issues. - How serious is a P0708 code?
This code can lead to significant drivability issues; thus, it should be addressed promptly. - Can I drive my car with a P0708 code?
While it’s possible to drive short distances, it’s not recommended due to potential damage to your transmission. - What tools do I need for diagnosing P0708?
An OBD-II scanner and basic hand tools for inspecting wiring and components are essential. - How much does it cost to fix a P0708 code?
The cost varies widely based on repairs needed but generally ranges from $50 up to several hundred dollars. - Can I fix P0708 myself?
If you have mechanical skills and tools, some aspects can be DIY; however, professional help is recommended for complex issues. - What happens if I ignore a P0708 code?
Ignoring this code can lead to severe transmission damage and costly repairs down the line.