P0706 on 2011-2018 Kia Forte: Transmission Range Sensor Causes and Fixes

What's Unique About the 2011-2018 Kia Forte

The 2011-2018 Kia Forte, particularly the second generation (YD, 2014-2018), is known for issues with its inhibitor switch. Kia issued a Technical Service Bulletin (TSB SA317B/C) for 2017 models, including the Forte, that specifically addresses problems stemming from this switch. The TSB covers symptoms like MIL illumination with code P0705, intermittent no-start, and erratic shifting, all directly related to the inhibitor switch failing. This makes the inhibitor switch a highly probable point of failure on these vehicles, a fact corroborated by numerous owner forums and shared experiences with its platform mate, the Hyundai Elantra.

Generation note: This range covers the first generation (TD, 2010-2013) and second generation (YD, 2014-2018). The primary cause, a faulty inhibitor switch, is common to both. A specific Technical Service Bulletin (SA317B/C) was issued for the 2017 YD model, indicating a documented issue with this part in the second generation for vehicles produced from June 28, 2016 through March 7, 2017.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle will not start, or only starts in Neutral
• Inability to shift the gear lever out of Park
• Harsh or delayed gear engagement
• Gear position indicator on the dashboard is incorrect, blank, or all positions are lit up at once
• Reverse lights do not work
• Vehicle enters 'limp mode' with reduced power and may be stuck in one gear (e.g., 4th)
• Slight engine stumble when shifting into Park after a long drive

Most Likely Causes

1. Faulty Transmission Range Sensor (Inhibitor Switch) 🔴 High Probability → Shop Transmission Assembly Kia issued a TSB (SA317B/C) for the 2017 Forte and other models due to inhibitor switch failures, acknowledging a known issue with the part's reliability for that model year. The high failure rate is widely discussed in owner forums for all years in this range.
   How to confirm: A mechanic can use a scan tool to monitor the live data from the sensor while moving the gear shifter. If the voltage readings are erratic, jumpy, or don't correspond to the correct gear position, the sensor is faulty. A DIY method involves testing continuity at the switch's pins for each gear position with a multimeter.
   Typical fix: Replace the Transmission Range Sensor (Inhibitor Switch). The switch is located on the outside of the transmission, typically under the air filter housing and battery tray. Proper alignment of the new switch during installation is critical.
   Est. part cost: $40-$130
2. Damaged Wiring or Corroded Connector 🟡 Medium Probability The sensor is located on the exterior of the transmission, exposing its wiring and connector to moisture, dirt, and road debris which can lead to corrosion or damage over time.
   How to confirm: Visually inspect the wiring harness and connector leading to the inhibitor switch for any signs of corrosion (green tinge), frayed wires, or loose pins. Perform a continuity test on each wire from the switch connector to the TCM connector with a multimeter to rule out an open or short in the harness.
   Typical fix: Clean the connector terminals with electrical contact cleaner and a small brush. Apply dielectric grease before reconnecting to prevent future corrosion. If the connector or wiring is damaged, it will need to be repaired or replaced.
   Est. part cost: $5-$50
3. Misadjusted Inhibitor Switch or Shift Cable ⚪ Low Probability → Shop Transmission Park Inhibitor Switch While less common, if the switch or the cable connecting the shifter to the transmission has been serviced before, it may have been improperly adjusted, causing the sensor's reported position to not match the actual gear. This can also happen due to vibrations over time.
   How to confirm: Verify that the gear selected by the driver matches the gear indicated on the transmission's manual lever. Check for excessive play in the shift cable and linkage. An improperly adjusted switch is a common cause of issues after a DIY replacement.
   Typical fix: Loosen the inhibitor switch mounting bolts, place the transmission lever in Neutral, and insert a 5mm drill bit or alignment pin into the alignment holes on the switch and the transmission body to ensure they are perfectly lined up. Tighten the bolts and remove the pin.
   Est. part cost: $0

Rare But Worth Checking

• Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM): → Shop Transmission Assembly This is extremely rare. All other possibilities, especially the sensor and its wiring, should be exhaustively ruled out before considering replacing a control module. One diagnostic video showed a case where the switch and wiring were good, but the computer itself was faulty.
• Dirty or Low Transmission Fluid: → Shop Transmission Assembly While this can cause many transmission issues, it's an indirect cause of P0706. It's more likely to trigger other codes first but is worth checking as part of a comprehensive diagnosis.

Diagnosis Steps

1. Connect an OBD-II scanner and confirm the presence of the P0706 code, noting any other codes that are present (especially P0705, P0707, P0708).
2. Use the scanner's live data function to monitor the Transmission Range Sensor output. Cycle the gear shifter through P, R, N, and D, and observe if the sensor data on the scanner matches each position correctly and without hesitation. A faulty switch will often show erratic or illogical readings.
3. If the data is erratic or incorrect, locate the inhibitor switch. On the Forte, this requires removing the air intake duct, the battery, and the battery tray to gain access.
4. Visually inspect the switch's connector and wiring harness for any signs of corrosion, damage, or loose connections. Clean as necessary.
5. If the wiring looks good, check the adjustment of the switch. With the transmission in Neutral, loosen the mounting bolts and use an alignment pin (or a 5mm drill bit) to align the switch correctly before retightening.
6. If the wiring and adjustment are correct but the sensor data is still faulty, the inhibitor switch is the most likely culprit and should be replaced.
7. After replacement, ensure the new switch is properly aligned using the method in step 5. This is a critical step.
8. Reassemble all components (battery tray, battery, air intake), clear the codes with the scanner, and perform a test drive to ensure the issue is resolved.

Parts You'll Likely Need

• Transmission Range Sensor / Inhibitor Switch (OEM #42700-3B700 (Superseded by 42700-26700)) — This is the most common point of failure for this code on this vehicle, with its failure mode being a known issue acknowledged by a manufacturer TSB.
  Trusted brands: Kia (Genuine OEM), ACROPIX, Rostra, Dorman
  OEM price range: $90-$130
  Aftermarket price range: $40-$70

Related Codes That Often Appear With This One

• P0705 — P0705 indicates a general malfunction in the same Transmission Range Sensor circuit. The TSB for the inhibitor switch on the 2017 Forte specifically mentions P0705 as a primary code for this issue.
• P0707, P0708, P0709 — These codes are also related to the Transmission Range Sensor, indicating low input, high input, or intermittent circuit failure, respectively. They often appear alongside P0706 and point to the same root cause.

Technical Service Bulletins (TSBs) & Recalls

• SA317B/C: Service Action for Inhibitor Switch Replacement on some 2017MY Forte (YD) vehicles produced from June 28, 2016 to March 7, 2017. It addresses concerns like no-start, erratic shifting, and MIL illumination with DTC P0705. This is a non-customer notification repair performed during the warranty period.
• Hyundai TSB 17-AT-005: While for Hyundai, this TSB covers the same 6-speed transmission and inhibitor switch DTCs (P0705, P0706, P0707, P0708), providing detailed diagnostic steps that are directly applicable to the Kia Forte.

Platform-Specific Known Issues

• A Technical Service Bulletin (SA317B/C) was issued by Kia for 2017 Forte models (among others) for inhibitor switch failure, which causes symptoms identical to those of a P0706 fault.
• The location of the switch under the battery and airbox makes replacement more time-consuming than on some other vehicles, increasing labor time slightly.

Mechanic-Grade Diagnostic Values

• Inhibitor Switch Continuity Test (Bench Test) — expected: With the switch removed, use a multimeter on the continuity/resistance setting. Connect one probe to the main power input pin. As you manually move the selector arm through each gear position, you should get continuity (a near 0 Ohm reading) on a different output pin for each position.. Failure: If a specific gear position does not result in continuity on any output pin, or if multiple pins show continuity at the same time, the switch has an internal fault.
• Inhibitor Switch Live Voltage Test (Back-probing) — expected: With the ignition on and connector plugged in, back-probe the signal wires at the switch. The voltage should change distinctly as you move the shifter through P, R, N, D. Generic expected values are approximately: Park ≈ 0V, Reverse ≈ 5V, Neutral ≈ 2.5V, Drive ≈ 4V.. Failure: Readings that are erratic, do not change with gear selection, or deviate by more than ~0.5V from the expected value point to a faulty sensor or wiring issue.

Scan Tool Commands That Help

• Kia GDS / Professional Bidirectional Scanner: Live Data Monitoring: 'Shift Lever Switch' or 'Transmission Range' — This is the primary diagnostic step to confirm the fault. It allows you to see the gear position the TCM is receiving in real-time as you move the shifter. If the displayed gear on the scanner does not match the physical shifter position, or if the reading is erratic, it strongly indicates a fault in the sensor or its circuit.
• Kia GDS / Professional Bidirectional Scanner: Special Function: 'Resetting Auto Transmission Adaptive Values' — This function should be performed AFTER replacing the inhibitor switch or performing any significant transmission repair. It clears the learned shift adaptations from the TCM, forcing it to relearn shift pressures and timing with the new components. Failing to do this can sometimes lead to persistent harsh or erratic shifting even after the part is replaced.

Wiring & Ground Locations

• Inhibitor Switch Connector — On the top or side of the transmission housing, typically located underneath the battery and battery tray. It has an 8-pin connector.. This is the primary point for visual inspection (corrosion, damage) and electrical testing (voltage, continuity) for the P0706 code.
• Transaxle Control Module (TCM) — Service diagrams show the TCM as a distinct module within the engine bay, separate from the main ECU/PCM on some models.. This module receives the signal from the inhibitor switch. If the switch and wiring are confirmed to be good, the TCM's connector would be the next place to test for a signal, though TCM failure itself is rare.

Real Owner Repair Stories

• forteforums.com user report (from Pass 2 analysis) (2014 Kia Forte) — Intermittent no-start condition where the engine would not crank.
  ❌ Tried (didn't work) Wiggling the gear shifter would temporarily allow the car to start.
  ✅ What actually fixed it The problem was permanently resolved by replacing the inhibitor switch (neutral safety switch).

OEM Part Supersession History

• 42700-3B700, 42700-3B100, 42700-26000, and others → 42700-26700 — Part has been revised multiple times by the manufacturer to improve reliability.
  Heads up: The latest part number, 42700-26700, is the correct and backward-compatible replacement for previous versions like 42700-3B700, 42700-3B500, 42700-26500, and others. There are no known incompatibilities when using the newest OEM part.

Model Year Variations Within This Range

• 2011-2013 (TD) vs 2014-2018 (YD): The Kia Forte underwent a full model change for the 2014 model year, moving to the 'YD' generation. While both generations primarily use a 6-speed automatic (A6GF1) and suffer from the same inhibitor switch failure, the body, interior, and some electronics are different. The TSB for inhibitor switch failure (SA317) specifically calls out 2017 models, suggesting a batch of faulty parts was used in that particular year.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Premature Engine Failure / Knocking (Nu, Gamma, Theta II Engines) 🔴 High — Widespread across multiple model years, particularly 2012-2015 and 2017. Can occur at mileage as low as 20,000-40,000 miles. Subject of recalls and class-action lawsuits. (Ref: Recalls SC210 (2017-2018 Forte w/ 2.0L Nu MPI for oil pump failure) and SC200 (engine fire risk).)
• MDPS Steering Coupler Failure 🟠 Medium — Very common across the 2014-2018 generation. Symptoms are a distinct clicking or knocking sound from the steering column when turning at low speeds. The part itself is inexpensive, but labor can be significant. (Ref: TSB CHA074 acknowledges the issue and provides a repair procedure to replace the flexible rubber coupler.)
• Engine Compartment Fire Risk 🔴 High — Affects certain 2012-2015 models. An electrical short in the Hydraulic Electronic Control Unit (HECU) can cause a fire while parked or driving. (Ref: NHTSA Recall 22V-031, among others, addresses this risk.)
• Malfunctioning Ignition Coils 🟡 Low — Reported on 2017 models around 20,000-40,000 miles, causing stalling, shaking, and misfiring.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, buying a used inhibitor switch is strongly discouraged. It is an electronic component with a very high, well-documented failure rate. The cost of a new aftermarket part is low enough that the risk and labor involved in potentially having to replace a used part twice outweighs any potential savings.

Donor-vehicle mileage cap: roughly under 30000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Inspect the plastic housing for any cracks or signs of heat stress.
• Check the electrical connector pins for any green or white corrosion.
• Ensure the metal lever arm is not bent or damaged.
• Verify the part number is the most recent supersession if possible.

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

• While not strictly OEM-only, using a Genuine Kia inhibitor switch (42700-26700) is highly recommended for peace of mind, given the known issues with this component.

Aftermarket brands forum-validated for this vehicle:

• Rostra
• Standard Motor Products (Ignition)
• Dorman
• Duralast

Brands owners have reported issues with on this vehicle:

• Unbranded, generic parts from online marketplaces should be avoided, as their internal components may not meet the required specifications, leading to premature failure or incorrect signals to the TCM.

Real Owner Stories

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

Related OBD-II Codes

• P0705 — Transmission Range Sensor Circuit Malfunction; often appears alongside P0706 and is specifically mentioned in Kia TSB SA317B/C regarding inhibitor switch failure.
• P0707 — Transmission Range Sensor Circuit Low Input; a companion code that may trigger if the inhibitor switch or wiring has a short or low voltage signal.
• P0708 — Transmission Range Sensor Circuit High Input; frequently diagnosed using the same steps as P0706, often involving the same faulty inhibitor switch or connector corrosion.

Frequently Asked Questions