P0706 on 2005-2014 Subaru Outback: Transmission Range Sensor Causes and Fixes

What's Unique About the 2005-2014 Subaru Outback

On these Subaru models, the inhibitor switch is mounted externally on the transmission case, making it susceptible to corrosion from road salt and moisture. While functionally similar across the model years, the part itself differs between the earlier 4/5-speed automatics and the later CVT transmissions introduced in 2010. Failure of this switch is a very well-documented issue in owner forums, with many owners successfully performing the repair themselves.

Generation note: This range covers two Outback generations: - 3rd Generation (2005-2009): Used a 4-speed (4EAT) or 5-speed (5EAT) automatic transmission. The inhibitor switch is a common failure point. - 4th Generation (2010-2014): Introduced the Lineartronic Continuously Variable Transmission (CVT), models TR580 (2.5L) and TR690 (3.6L), on 4-cylinder models, while 6-cylinder models retained a 5-speed automatic. The inhibitor switch design and part number differ between the conventional automatic and the CVT.

Symptoms You May Notice

• Check Engine Light is on
• Flashing 'AT OIL TEMP' light on the dashboard
• Vehicle will not start when the shifter is in Park, but may start in Neutral
• Incorrect or no gear position displayed on the instrument cluster (PRNDL)
• Reverse lights do not turn on
• Transmission enters 'limp mode,' often stuck in 3rd gear
• Harsh or delayed gear engagement
• Cruise control is disabled

Most Likely Causes

1. Faulty Inhibitor Switch (Neutral Safety Switch) 🔴 High Probability The switch is mounted on the side of the transmission, exposing it to road grime, salt, and moisture, which can lead to internal corrosion and failure. Some owners have successfully disassembled and cleaned the internal contacts as a temporary fix, but this is often short-lived.
   How to confirm: After confirming the switch is properly adjusted, test for correct continuity at the switch's electrical connector for each gear position using a multimeter, as per the factory service manual. An inconsistent or failed reading in any position indicates a bad switch. Many owners report that the switch fails when hot and may test good when cold.
   Typical fix: Replace the inhibitor switch and perform an alignment procedure. Using a genuine Subaru part is highly recommended by forum users for longevity.
   Est. part cost: $60 - $150
2. Inhibitor Switch Misalignment 🟡 Medium Probability Vibrations or previous service can cause the switch to rotate slightly on its mounting bolts, leading to incorrect gear position readings.
   How to confirm: Place the transmission shift lever in Neutral. Loosen the switch's mounting bolts and rotate it until the alignment hole on the switch body lines up with the corresponding hole on the selector lever. A 5.5mm drill bit or a similarly sized pin is commonly used to confirm perfect alignment.
   Typical fix: Re-align the inhibitor switch and tighten the mounting bolts. If symptoms persist, the switch is likely faulty.
   Est. part cost: $0
3. Damaged Wiring or Corroded Connector ⚪ Low Probability The wiring harness leading to the switch is located under the vehicle and can be damaged by road debris or develop corrosion at the connector pins. The connector itself can become brittle with age.
   How to confirm: Visually inspect the wiring harness for any signs of chafing, breaks, or heat damage. Disconnect the inhibitor switch connector and check for green or white corrosion on the pins and terminals. Test for power and ground at the connector with a multimeter.
   Typical fix: Repair the damaged section of wiring or clean/replace the connector.
   Est. part cost: $10 - $50

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): This is extremely rare. The TCM should only be considered after definitively ruling out the switch, wiring, and adjustment as the cause of the problem. A full diagnostic scan with a Subaru-specific tool would be needed to condemn the TCM.

Diagnosis Steps

1. Scan the vehicle for all trouble codes. Confirm P0706 is present, likely with P0700.
2. Check for Technical Service Bulletins (TSBs) or recalls related to this code for your specific year and model. Note that while no specific TSB for P0706 on this part exists for this year range, later models were recalled for a similar issue.
3. Attempt to start the vehicle in both Park and Neutral. If it starts in Neutral but not Park, this strongly points to an inhibitor switch issue.
4. Check the operation of the reverse lights when shifting into Reverse.
5. Raise the vehicle safely. Locate the inhibitor switch on the passenger side of the transmission case, where the shift cable connects.
6. Inspect the wiring and connector for any visible damage, corrosion, or loose connections.
7. Check the switch alignment. Place the shifter in Neutral and see if the alignment marks/holes on the switch and lever line up. A 5.5mm drill bit is a useful tool for this. If not, attempt to adjust it.
8. If adjustment does not resolve the issue, disconnect the switch and test for continuity across the pins for each gear position using a multimeter, following the vehicle's service manual procedure.
9. If the switch fails the continuity test, it is faulty and must be replaced.
10. If the switch tests good, the problem is likely in the wiring harness between the switch and the TCM. A pin-to-pin continuity and resistance check of the harness is required.

Parts You'll Likely Need

• Inhibitor Switch (For 4EAT/5EAT Transmissions) (OEM #31918AA090) — This is the component that fails most frequently on 2005-2009 models and 6-cylinder 2010-2014 models with conventional automatic transmissions.
  Trusted brands: Subaru (Genuine)
  OEM price range: $80-$120
  Aftermarket price range: $50-$90
• Inhibitor Switch (For CVT Transmissions) (OEM #31918AA101 (replaces 31918AA100)) — This is the corresponding part for 2010-2014 models equipped with the Lineartronic CVT. It is not interchangeable with the 4EAT/5EAT switch.
  Trusted brands: Subaru (Genuine)
  OEM price range: $100-$150
  Aftermarket price range: $70-$110

Related Codes That Often Appear With This One

• P0700 — P0700 is a generic code indicating the Transmission Control Module (TCM) has requested the Check Engine Light to be turned on. It is almost always present alongside a more specific transmission code like P0706.

Technical Service Bulletins (TSBs) & Recalls

• While there is no direct TSB for P0706 on the 2005-2014 Outback's inhibitor switch, related bulletins exist. TSB 16-102-16R and 16-103-16R address other CVT issues that can cause the AT OIL TEMP light to flash, such as valve body problems or fluid seepage. It's important to correctly diagnose P0706 to avoid confusing it with these other known CVT problems.

Platform-Specific Known Issues

• Subaru extended the warranty on some CVT transmissions (Warranty Enhancement Program ZV-68) for certain model years due to issues like shuddering and valve body failure, but this warranty extension does not specifically cover the external inhibitor switch. A P0706 code points to the switch, not the internal components covered by the extension.
• A recall (WRQ-23 / NHTSA 23V-755) was issued for a faulty inhibitor switch on newer (2021-2023) Outbacks due to water intrusion from a bad weld, demonstrating a history of issues with this component's design and placement.

Mechanic-Grade Diagnostic Values

• Inhibitor Switch Continuity Test (4EAT/5EAT) — expected: With the switch connector disconnected, there should be continuity between specific pin pairs depending on the gear selected. For example, in Park, there should be continuity between the pins for the starter relay circuit. In Reverse, there should be continuity between the pins for the reverse lights. Each gear position has a unique combination of closed circuits.. Failure: No continuity on a circuit that should be closed, or continuity on a circuit that should be open for a given gear selection. This test must be performed for every gear position.

Scan Tool Commands That Help

• Subaru Select Monitor: Current Data Display & Save > Range Switch — To live-monitor the gear position signal being sent to the TCM. While shifting through the gears (P, R, N, D), the technician can watch the data display to see if the switch is reporting the correct position instantly and without glitches. An incorrect or delayed reading confirms a problem in the switch or its circuit.
• Subaru Select Monitor: Clear Memory — After the repair (switch replacement or adjustment) is complete, this function is used to clear the P0706 and P0700 codes from the TCM's memory. This is a necessary step before test driving to confirm the fix.

Wiring & Ground Locations

• Transmission Ground Strap — A braided ground strap typically running from the top or side of the transmission case to a bolt on the vehicle's chassis/frame rail, often near the passenger side strut tower.. A corroded or loose transmission ground can cause a variety of electrical issues, including erratic sensor readings. While it may not directly cause P0706, it can create electrical noise that interferes with the inhibitor switch signal, complicating diagnosis. Ensuring this ground is clean and tight is a crucial step in any electrical diagnosis.
• Engine Ground (Intake Manifold) — Ground wires bolted directly to the top of the intake manifold. These are the primary ground points for the ECU and its sensors.. The TCM and ECU rely on a stable ground reference. A poor ground at the intake manifold can cause voltage offsets and unstable sensor readings across the entire engine and transmission management system, potentially leading to false codes.
• Inhibitor Switch Connector — Directly on the inhibitor switch, located on the passenger side of the transmission where the selector lever attaches.. This is the primary point of failure for wiring issues. The connector is exposed to the elements and can fill with moisture, causing corrosion on the pins which leads to poor signal quality and the P0706 code.

Real Owner Repair Stories

• Reddit user on r/subaru (2008 Subaru Legacy GT (5EAT)) — AT OIL TEMP light flashes and car struggles to start (no-crank) only after driving for 30+ minutes (when hot). A short 20-minute drive causes no issues. Shifting through the gears and back to Park sometimes allows it to start.
  ❌ Tried (didn't work) Initial thought was misalignment, but the issue was heat-dependent and repetitive, making misalignment unlikely.
  ✅ What actually fixed it The consensus from other users was a failing inhibitor switch. The internal contacts develop high resistance when heated by the transmission, causing the signal to drop out. The switch works fine when cold. The fix is to replace the external inhibitor switch.

OEM Part Supersession History

• 31918AA100 → 31918AA101 — Likely an internal revision for improved durability or material changes.
  Heads up: These parts are for CVT models only and are not compatible with the 4EAT/5EAT transmissions which use part number 31918AA090.

Model Year Variations Within This Range

• 2005-2009 (and 2010-2014 3.6R): These models use the 4EAT or 5EAT conventional automatic transmission. The correct inhibitor switch is part number 31918AA090.
• 2010-2014 (2.5i): These models use the Lineartronic CVT (TR580). The correct inhibitor switch is part number 31918AA101 (or its predecessor). This part is not interchangeable with the one for the conventional automatic.
• All: The alignment procedure for the inhibitor switch requires a pin to be inserted through the switch body and lever when the shifter is in Neutral. While many forum users report using a 5.5mm drill bit, some service documents have specified a 4mm or 1.5mm pin depending on the exact transmission generation, indicating minor variations in the alignment hole size over the years.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• EJ253 Engine Head Gasket Failure 🔴 High — Extremely common on models up to 2012, typically between 80,000-150,000 miles. Usually presents as external oil and/or coolant leaks.
• Lineartronic CVT Failure (TR580/TR690) 🔴 High — Common on 2010-2014 models. Issues include torque converter lock-up failure, valve body solenoid failure, and chain slip, causing shuddering, hesitation, or stalling. Led to a class-action lawsuit and warranty extension (up to 10 years/100,000 miles). (Ref: Subaru Warranty Extension Program (WEP) ZV-68)
• Front Lower Control Arm Bushing Failure 🟠 Medium — The large, fluid-filled rear bushing on the front control arm frequently tears or leaks, typically before 100,000 miles, causing clunking noises over bumps and poor alignment.
• Premature Wheel Bearing Failure 🟠 Medium — Common on all model years. Presents as a loud roaring or humming noise that increases with vehicle speed and changes pitch when turning. Often requires replacement before 100,000 miles.
• Catalytic Converter Inefficiency (P0420) 🟡 Low — Very common on higher-mileage Subarus. While it doesn't affect drivability, it will cause a persistent Check Engine Light and failure of emissions tests. Often caused by an aging front oxygen sensor before the converter itself fails.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used inhibitor switch from a junkyard can be a cost-effective option, especially for older models, as it is an external, easily-swapped part. However, it is a known failure item, so it carries some risk.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Check the donor vehicle's mileage; lower is always better.
• Inspect the plastic housing for cracks or signs of extreme heat exposure.
• Examine the electrical connector pins for any corrosion or damage. Avoid any part with green or white residue on the pins.
• If possible, ask about the history of the donor car (e.g., was it in a front-end collision that could have damaged the transmission area?).
• Prefer donors from dry, non-salt-belt regions to minimize the risk of internal corrosion.

OEM-only on this vehicle (don't cheap out):

• While not strictly 'OEM-only', forum consensus strongly favors using a Genuine Subaru inhibitor switch. Aftermarket versions have a reputation for premature failure, sometimes within a year, making the cost savings negligible in the long run.

Brands owners have reported issues with on this vehicle:

• Generic, unbranded switches from online marketplaces are frequently cited as unreliable.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0700 — This is a generic Transmission Control System Malfunction code. It is almost always stored alongside P0706 because it acts as a general alert that the Transmission Control Module (TCM) has detected a specific fault, which in this case is the P0706.

Frequently Asked Questions