P0705 on 2011-2018 Mercedes-Benz CLS-Class: Transmission Range Sensor Fault Causes and Fixes

What's Unique About the 2011-2018 Mercedes-Benz CLS-Class

Unlike many vehicles with an external, easily replaceable transmission range sensor, the 2011-2018 CLS-Class with the 7G-Tronic (722.9) transmission has this sensor (designated Y3/8s1) integrated directly into the electronic conductor plate. This assembly, also known as the Valve Body Control Unit or Mechatronic, is located inside the transmission oil pan. As a result, a P0705 fault is not a simple sensor swap but points to a failure of the entire conductor plate, a well-documented issue on this platform due to internal electronic faults, often related to heat and vibration.

Generation note: The 2011-2018 range primarily covers the C218 generation of the CLS-Class. The 2018 model year also saw the introduction of the C257 generation, some of which still used the 7G-Tronic before the 9G-Tronic became standard. Both generations use automatic transmissions where the range sensor is part of the internal control unit, making this guide relevant to both, though the C218 with the 722.9 transmission is where this issue is most commonly documented.

Symptoms You May Notice

• Transmission is stuck in one gear (limp mode).
• Check Engine Light is on.
• Harsh or erratic shifting, sometimes with a loud 'thump' when selecting Drive or Reverse.
• Gear indicator on the dashboard (PRND) is blank, incorrect, or does not update.
• Vehicle will not start (if the computer cannot confirm the transmission is in Park or Neutral).
• Inability to shift out of Park.
• Message on dash: 'Transmission - Visit Workshop'.

Most Likely Causes

1. Failed Transmission Conductor Plate (TCU/VGS) 🔴 High Probability → Shop Transmission Assembly The transmission range sensor (Y3/8s1) is integrated into the conductor plate, which is a known failure point on the 722.9 transmission. Failure is often due to delamination of internal electrical traces or failure of the onboard speed sensors (Y3/8n1, Y3/8n2) which are also part of the unit.
   How to confirm: A Mercedes-specific diagnostic scanner (like STAR/XENTRY) is needed to read detailed fault codes from the transmission control unit. Code P0705 specifically points to the internal range sensor circuit. Often, it will be accompanied by speed sensor codes like 0717, 0718, 2767, or 2768, which confirm an internal plate failure.
   Typical fix: There are two main repair paths: 1) Replace the conductor plate with a new OEM part, which then requires SCN programming. 2) Remove the original conductor plate and send it to a specialist service for repair and rebuild. 🎬 Watch: How to remove the conductor plate for repair This is often cheaper and requires no programming upon reinstallation. 🎬 See this step-by-step conductor plate installation guide
   Est. part cost: $600-$900 for a new OEM plate; $200-$400 for a rebuild service.

Rare But Worth Checking

• Low or Contaminated Transmission Fluid: → Shop Transmission Assembly While less common for this specific code, very low or burnt fluid can cause a range of erratic transmission behaviors. It's a basic check that should be performed first. Fluid contamination with coolant (from a failed radiator heat exchanger) can also destroy the electronics.
• Leaking Transmission Connector Plug (Pilot Bushing): → Shop Transmission Assembly The 13-pin electrical connector sleeve on the transmission is a common leak point. While more famous for causing issues on the older 722.6 transmission, a severe leak on the 722.9 can still cause communication problems. In very rare cases, fluid can wick up the wiring harness to the main TCU (if located externally on older models), but for the CLS-Class, the primary issue is a poor connection at the transmission itself.
• Faulty Gear Selector Module (ESM): The shifter assembly in the center console can fail, but this typically generates different, specific fault codes related to the ESM itself. It is often misdiagnosed as the cause of P0705, but live data from a scanner can usually show the ESM is sending correct signals, isolating the fault to the transmission's internal range sensor.

Diagnosis Steps

1. Scan the vehicle with a Mercedes-Benz compatible scanner (XENTRY/DAS) to confirm P0705 and check for other related transmission codes like 0717, 0718, 2767, or 2768.
2. Check the transmission fluid level and condition using the proper procedure for the 722.9 transmission (which does not have a traditional dipstick).
3. Inspect the main 13-pin electrical connector at the transmission for any signs of fluid contamination or corrosion. If wet, the connector sleeve should be replaced.
4. If fluid and wiring are okay, the fault is almost certainly internal to the transmission conductor plate. One owner noted the fault only appeared when the transmission was hot.
5. Confirm the diagnosis with a specialist who can analyze live data from the range sensor and speed sensors.
6. Choose a repair path: replace with a new, programmed plate or repair the original unit.

Parts You'll Likely Need

• Transmission Conductor Plate (VGS) (OEM #A0002702600 (VGS3), A0002701700 (VGS3), A0335457332 (VGS2). Verify by VIN.) — This is the primary failure point for a P0705 code, as it contains the integrated transmission range sensor. There are different versions (VGS1, VGS2, VGS3); the CLS-Class C218 typically uses VGS2 or the later VGS3.
  Trusted brands: Mercedes-Benz (OEM), Continental (OEM supplier), Various rebuild services (e.g., Circuit Board Medics, ACTRONICS)
  OEM price range: $700-$900
  Aftermarket price range: $250-$500 (Remanufactured/Repaired)
• Transmission Pan Gasket, Filter, and Bolts — These are single-use or essential replacement items for any service that involves dropping the transmission pan to access the valve body.
  Trusted brands: Mercedes-Benz, Elring, Vaico, Febi
  OEM price range: $50-$80
  Aftermarket price range: $30-$50
• MB 236.14 / 236.15 Spec ATF — The transmission fluid must be drained to perform the repair and refilled with the correct specification fluid. The 7G-Tronic Plus (from ~2010) uses a different, lower-viscosity fluid (236.15) than the original 7G-Tronic (236.14). Using the wrong fluid can cause damage.
  Trusted brands: Mercedes-Benz, Fuchs Titan, Shell ATF 134, Liqui Moly Top Tec ATF 1600
  OEM price range: $20-$25 per liter
  Aftermarket price range: $12-$18 per liter
• Transmission Connector Plug Adapter (Pilot Bushing) (OEM #A2212770198 or similar (verify by VIN)) — This connector sleeve is a very common source of transmission fluid leaks. It is inexpensive and should be replaced as a preventative measure whenever the pan is off.
  Trusted brands: Mercedes-Benz, Febi
  OEM price range: $15-$25
  Aftermarket price range: $10-$15

Related Codes That Often Appear With This One

• 0717 / 0718 — These codes indicate a fault with the Turbine Speed Sensor (Y3/8n1), which is physically part of the same conductor plate. Their presence alongside P0705 strongly confirms conductor plate failure.
• 2767 / 2768 — These codes indicate a fault with the Internal Speed Sensor (Y3/8n2), also located on the conductor plate. Seeing these with P0705 is a definitive diagnosis for a failed plate.

Platform-Specific Known Issues

• The conductor plate on the 7G-Tronic (722.9) transmission is a widely recognized failure item that can fail at relatively low mileage. One owner on MBWorld reported failure at just 57,000 miles.
• Replacement of the conductor plate is considered a 'theft-relevant' part by Mercedes-Benz and requires online SCN coding, meaning most DIYers and many independent shops cannot complete the repair without dealer involvement or specialized tools like Autel MaxiSYS or a remote programming service.
• There are multiple hardware versions of the conductor plate (VGS1, VGS2, VGS3). A replacement must be the correct version for the vehicle. Upgrading from VGS2 to a newer VGS3 is possible but requires specific programming knowledge.

Mechanic-Grade Diagnostic Values

• Metal buildup on range selector magnet — expected: Clean magnet on the control valve.. Failure: An excessive buildup of metallic filings on the magnet can interfere with the hall sensor's reading, causing implausible signals.

Hidden / Shadow Codes Worth Checking

• P2805: The signal from components Y3/8s1 (selection range sensor) and/or A80 (intelligent servo module for Direct Select) is not plausible. This code is often stored along with P0705. (see via This code is typically visible with a Mercedes-specific scanner like XENTRY.)
• 0705: Component Y3/8s1 (selection range sensor (VGS)) is defective.: This is the Mercedes-specific definition of the P0705 fault, directly naming the internal conductor plate sensor Y3/8s1 as the defective component. (see via Mercedes STAR/XENTRY diagnostic system.)

Scan Tool Commands That Help

• XENTRY/DAS: Initial Start-Up of Control Unit — This is a mandatory, guided procedure when installing a new, 'virgin' conductor plate. It includes SCN coding, drive authorization, and teaching the selection range sensor.
• XENTRY/DAS: Personalize and Activate Control Unit — After installing a new conductor plate, this function 'marries' the new part to the vehicle's VIN and enables it on the CAN bus network.
• XENTRY/DAS: Teaching of selection range sensor — This is a specific step within the 'Initial Start-Up' process that calibrates the newly installed range sensor to the gear positions. It can sometimes be run independently to retrain the sensor, but there is a risk of immobilizing the vehicle if the process fails.

Real Owner Repair Stories

• MBWorld.org Forums user 'rgfinn76' (Mercedes-Benz with 57,000 miles) — P0705 code present, but car drove fine. The code would only trigger after a long drive and would appear upon the next restart.
  ❌ Tried (didn't work) Clearing the code (it returned a few days later).
  ✅ What actually fixed it Replacement of the conductor plate on the valve body. The user noted that even at low mileage, the fault can occur, especially when the unit is hot. The final repair was done at a dealer due to the need for programming.

OEM Part Supersession History

• VGS2 Conductor Plate → VGS3 Conductor Plate — VGS3 is a newer, updated version of the conductor plate.
  Heads up: Upgrading from a VGS2 to a VGS3 is possible but is not a direct swap. It requires specific knowledge to transfer flow data from the old plate and perform the correct SCN coding and software flashing for the new hardware.
• A0002701700 (VGS3) → A0002702600 (VGS3) — Internal revision and component updates by the manufacturer.
  Heads up: These parts are generally interchangeable as they are both VGS3 units, but it is always critical to verify the correct part number for the vehicle's VIN before ordering.

Model Year Variations Within This Range

• 2011-2018: The 722.9 transmission had several versions of the conductor plate (VGS1, VGS2, VGS3). Earlier models in this range may have a VGS2 plate, while later models will have a VGS3. While the P0705 fault is common to both, the replacement part numbers are different, and a VGS2 cannot be replaced with a VGS3 without advanced programming. It is essential to identify the installed plate version before ordering a replacement.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Airmatic Suspension Failure 🔴 High — Common after 5-8 years or 60,000-80,000 miles. Leaking air struts/springs or failing compressors are typical. (Ref: No official recall, but a widely documented issue.)
• M276 Engine: Timing Chain Rattle on Startup 🟠 Medium — Primarily affects earlier M276 engines (pre-2014). Caused by faulty timing chain tensioners and a lack of oil pressure at startup. (Ref: Mercedes issued service bulletins and updated parts (new check valves and tensioners) to address the problem.)
• M276 Engine: Oil Leaks into Camshaft Position Sensors 🟠 Medium — Oil can leak from the camshaft magnets/sensors and wick through the wiring harness, potentially damaging the engine control unit (ECU). (Ref: No recall, but a well-known issue. Preventative replacement of sensors and installation of sacrificial pigtail harnesses is a common owner practice.)
• COMAND Infotainment System Glitches 🟡 Low — Owners report issues like screen freezing, Bluetooth connectivity problems, or loss of navigation. Often requires a software update or, in rare cases, hardware replacement.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A 'used' part from a junkyard is almost never a smart choice for this repair. The conductor plate is a theft-relevant part that is 'married' to the original vehicle's VIN. A used plate must be 'virginized' (reset) by a specialist with bench tools before it can be programmed to a new car, and even then, success is not guaranteed. The only viable non-new option is to send your *original* conductor plate to a specialist for repair and rebuilding. This avoids all programming and coding issues.

Donor-vehicle mileage cap: roughly under 40000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Not applicable for junkyard parts due to programming locks.
• For a rebuild service, choose a company with a solid warranty and good reviews on Mercedes forums.
• Ensure the rebuild service explicitly states they repair the range sensor (Y3/8s1) fault, not just the more common speed sensor faults.

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

• Transmission Conductor Plate (VGS/TCU). While rebuilds are viable, if buying a replacement unit, it MUST be a new OEM part from a dealer or authorized supplier to ensure it is 'virgin' and can be programmed via SCN coding.

Aftermarket brands forum-validated for this vehicle:

• ACTRONICS (Rebuild Service)
• Circuit Board Medics (Rebuild Service)
• UpFix (Rebuild Service)

Brands owners have reported issues with on this vehicle:

• Unknown/unbranded 'virginized' or 'pre-programmed' conductor plates from online marketplaces. These often fail to program or are defective units.

Real Owner Stories

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

Related OBD-II Codes

• 0717 — Internal speed sensor (Y3/8n1) signal failure; frequently accompanies P0705 when the conductor plate fails.
• 0718 — Component Y3/8n1 (Turbine speed sensor) is defective; a common companion code for conductor plate internal range sensor issues.
• 2767 — Internal speed sensor (Y3/8n2) signal unavailable; confirms internal conductor plate failure alongside P0705.
• 2768 — Component Y3/8n2 (Internal speed sensor) is defective; often seen with range sensor circuit faults on the 722.9 transmission.

Frequently Asked Questions