Fix P0708: Transmission Range Sensor A Circuit High Input – Trust iCarsoft CR MAX BT
If your vehicle fails to start, displays incorrect gear positions, or the check engine light illuminates with OBD2 code P0708, you’re dealing with a critical transmission control fault. P0708 signals “Transmission Range Sensor (TRS) A Circuit High Input”—a problem where the sensor monitoring your gear selector position sends abnormally high voltage to the Transmission Control Module (TCM) or Engine Control Unit (ECU). Ignore it, and you’ll face inability to shift gears, no-start issues, or even transmission damage from incorrect torque converter lockup.
But diagnosing P0708 doesn’t have to mean costly dealership visits. In this guide, we’ll break down P0708 in plain English: what it is, common causes, red-flag symptoms, and how the iCarsoft CR MAX BT diagnostic tool (with wireless Bluetooth) simplifies troubleshooting for DIYers and mechanics. Plus, we’ll share real customer reviews, 8 FAQs, and show you how to fix P0708 at home. Let’s get your transmission range sensor (also called a “neutral safety switch”) working reliably again!
What Is OBD2 Code P0708?
P0708 is a standard OBD2 diagnostic trouble code defined as “Transmission Range Sensor (TRS) A Circuit High Input”. The transmission range sensor is a key component of automatic transmissions: it communicates the gear selector position (Park, Reverse, Neutral, Drive, etc.) to the TCM/ECU. This data ensures the engine starts only in Park/Neutral, enables proper shift timing, and prevents torque converter lockup in incorrect gears.
The TRS sends a voltage signal (typically 0.5–4.5V) to the TCM/ECU, with specific voltages corresponding to each gear. When the TCM detects the signal exceeds the normal range (often above 5V) for an extended period, it triggers P0708. This code applies to all automatic transmission vehicles (cars, trucks, SUVs) and indicates a fault in the TRS, wiring, or TCM—all requiring prompt attention to avoid dangerous driving conditions.
Top 5 Causes of P0708
Faulty Transmission Range Sensor (TRS)
The #1 culprit—internal electrical failure in the TRS (e.g., worn contacts, damaged circuits) causes high-voltage signals to the TCM/ECU.
Damaged Wiring/Connectors
Corrosion, fraying, or short circuits between the TRS and TCM/ECU create voltage spikes in the circuit, triggering high-input readings.
Dirty/Contaminated TRS Connector
Debris, moisture, or corrosion on the sensor connector disrupts signal flow, leading to false high-input readings.
Malfunctioning TCM/ECU
Rare, but outdated firmware or internal damage to the TCM/ECU may misinterpret TRS data, triggering false P0708 codes.
Incorrect Gear Selector Alignment
A misaligned gear shifter (e.g., loose linkage) puts pressure on the TRS, causing it to send abnormal high voltages.
Common Symptoms of P0708 to Watch For
Don’t ignore these warning signs—they mean your transmission range sensor is failing and pose a safety risk:
-
Illuminated check engine light (MIL) or dedicated transmission warning light on the dashboard.
-
Incorrect gear position display (e.g., shows “Drive” when in Park or “Neutral” when in Reverse).
-
Engine won’t start (only cranks) or starts in non-Park/Neutral gears (serious safety hazard).
-
Rough or delayed gear shifts (TCM uses incorrect gear position data for shift timing).
-
Transmission stuck in “limp mode” (limits speed to ~30 mph to protect the system).
-
Torque converter lockup issues (e.g., stays locked in gear, causing engine stalling).
Why iCarsoft CR MAX BT Is Your Best Tool for P0708
Basic OBD scanners can only read P0708—they can’t test the TRS or verify TCM communication. The iCarsoft CR MAX BT, equipped with wireless Bluetooth and advanced transmission diagnostics, gives you professional-grade tools to pinpoint the root cause of high-input issues from your smartphone/tablet, no tangled cables required. Here’s how it outperforms basic scanners:
Transmission System Specialization
Reads P0708 and detailed subcodes to target the exact issue (e.g., “TRS Circuit High Voltage in Park”).
Bluetooth Wireless Connectivity
Syncs with iOS/Android devices for cable-free operation—perfect for accessing under-dash TRS connectors.
Live Data Streaming
Monitors real-time TRS voltage, gear position data, and TCM communication to confirm high-input signals.
Bidirectional Control
Simulates gear position commands to test the TRS—critical for ruling out sensor failure vs. wiring problems.
TCM Adaptation Reset
Resets the TCM post-repair to recognize new TRS data—no dealership tools needed.
Multi-Brand Compatibility
Works with 60+ global brands (Ford, Toyota, BMW, Mercedes-Benz, Honda, Volkswagen, and more).
Intuitive Mobile App
Step-by-step prompts, AutoVIN identification, and 15-language support make it beginner-friendly.
Lifetime Free Updates
Stays compatible with new transmission models and updated diagnostic protocols—no recurring fees.
Pro Tip: The CR MAX BT’s live TRS voltage tracking lets you compare readings across gears—confirming if the sensor is faulty (erratic high voltages) or the issue is wiring (consistently high voltage in all gears). Shop the iCarsoft CR MAX BT Now →
Real Customer Reviews: How the CR MAX BT Fixed P0708
Drivers trust the CR MAX BT to solve P0708 and avoid costly dealership transmission control repairs—here’s what they’re saying:
I got P0708 on my 2018 Ford F-150 and was quoted $450 by the dealership (TRS + labor). Bought the iCarsoft CR MAX BT, paired it with my iPhone, and scanned in 60 seconds—found a faulty transmission range sensor. Replaced it for $70 and used the tool to reset the TCM. My truck starts perfectly now, and the gear display is accurate—saved over $380! Bluetooth makes it so easy to monitor voltage while testing gears. — Tyler M., Truck Owner
As a mobile mechanic, I see P0708 often in older vehicles with wiring wear. The CR MAX BT has fixed it on Toyota Camrys, BMW X5s, and Honda Accords. The bidirectional TRS test is a game-changer—lets me confirm if the sensor is faulty without disassembling the gear shifter. Wireless sync is seamless, and the app’s live data saves me hours of troubleshooting. Worth every penny for professionals and DIYers alike! — Sarah L., Independent Mechanic
I’m not mechanically savvy, but the CR MAX BT made P0708 simple. Paired it with my Android phone, followed the prompts, and found a corroded TRS connector. Cleaned it with $10 electrical contact cleaner and cleared the code—my 2017 Hyundai Tucson now starts in Park/Neutral and shifts smoothly. Avoided a $600 shop bill for unnecessary transmission repairs. The Bluetooth feature means no tangled cables—total win! — David K., Daily Commuter
FAQs: Your P0708 & CR MAX BT Questions Answered
Can I Drive With P0708?
No—P0708 poses serious safety risks (e.g., engine starting in gear, inability to shift properly). If the vehicle starts and shifts, limit driving to short trips (under 5 miles) and fix the issue immediately to prevent accidents or transmission damage.
How Much Does It Cost to Fix P0708?
Costs vary based on the root cause: A TRS replacement costs $50–$200 (parts only); wiring/connector repairs cost $10–$50; TCM firmware updates cost $100–$200; dealership diagnostic and repair costs $200–$1,000+. The CR MAX BT helps you avoid overpaying for unnecessary TCM work by pinpointing the exact issue.
Will the CR MAX BT Work With My Vehicle?
The CR MAX BT supports over 60 global vehicle brands with automatic transmissions, including Asian (Toyota, Honda, Hyundai), European (BMW, Mercedes-Benz, Volkswagen), and American (Ford, GM) models. Check the official iCarsoft compatibility list for your specific make, model, and year.
How Do I Use the CR MAX BT to Diagnose P0708?
1. Download the iCarsoft app and pair the tool with your phone via Bluetooth.
2. Plug the CR MAX BT into your vehicle’s OBDII port (usually under the dashboard).
3. Turn on the ignition (don’t start the engine) → Select “Transmission System” → “Read DTCs” to view P0708 and a detailed description.
4. Go to “Live Data” → Monitor “Transmission Range Sensor Voltage” while shifting gears—readings above 5V confirm the high-input issue.
Can the CR MAX BT Clear P0708 Permanently?
Yes—after fixing the root cause (e.g., replacing the TRS, cleaning the connector). Select “Clear DTCs” in the app, then test drive the vehicle while monitoring gear position data to confirm normal voltage readings and ensure the code does not reoccur.
Do I Need Mechanical Experience to Use the CR MAX BT?
No—its user-friendly mobile app includes AutoVIN identification, step-by-step troubleshooting prompts, and multilingual support (15 languages) that make it accessible for beginner DIYers with no mechanical experience.
What If P0708 Comes Back After Clearing It?
If the code returns, the root cause was not fully fixed (e.g., hidden wiring damage, a failing TCM, or misaligned gear selector). Use the CR MAX BT’s live data streaming and bidirectional TRS tests to troubleshoot further and identify the unresolved issue.
Does the CR MAX BT Offer Other Transmission-Related Functions?
Yes—beyond P0708, it can test output/input speed sensors, monitor torque converter lockup, perform TCM resets, and diagnose related transmission control codes like P0705 (TRS Circuit Malfunction) or P0706 (TRS Circuit Range/Performance).
Final Thoughts: Don’t Let P0708 Disable Your Transmission
OBD2 code P0708 is a critical but fixable transmission control issue—with the right diagnostic tool. The iCarsoft CR MAX BT combines wireless Bluetooth convenience with professional-grade transmission diagnostics, letting you pinpoint faulty TRS sensors, wiring problems, or alignment issues and fix them at home without expensive dealership markups.
Whether you’re a casual car owner, DIY enthusiast, or professional mechanic, the CR MAX BT’s durability, multi-brand coverage, and lifetime free updates make it a long-term investment in your vehicle’s safety and performance. Fix P0708, restore safe gear shifting, and protect your transmission from costly damage—all with one seamless, cable-free diagnostic tool.
Ready to tackle P0708 head-on? Click here to get the iCarsoft CR MAX BT and unlock professional transmission control diagnostics for your garage! Have questions about P0708 or the CR MAX BT? Drop a comment below—we’re here to help!
