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Mercedes-Benz · Known Issues

2017 Mercedes-Benz GLS Problems: 5 Known Issues

2017 model year · 2,600+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 2,600+ owner reports, the 2017 Mercedes-Benz GLS has 5 documented known issues, with 2 rated critical. The most serious are AIRMATIC Air Suspension Failure ($800-$4,000 repair) and Electric Power Steering Rack Connector Water Intrusion Causing Loss of Steering Assist (Recall 17V241) ($0-$4,500 repair). The most commonly reported issue is AIRMATIC Air Suspension Failure with 1,500 owner reports. Across all issues with published estimates, repair costs range from $150 to $4,500. DIY maintenance guides at au7o.io.

In This Article

  • GLS Suspension1
  • GLS Steering1
  • GLS Engine2
  • GLS Transmission1
  • FAQ
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In This Article

  • Suspension1
  • Steering1
  • Engine2
  • Transmission1

All 5 Known Issues

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Community reported
1,500 owners

On the 2017-2023 Mercedes-Benz GLS, the GLS AIRMATIC system is prone to air spring leaks and compressor failure due to the vehicle's heavy curb weight (5,700+ lbs). Front air springs tend to fail first. The compressor overworks to maintain ride height and eventually burns out.

Common Symptoms

  • Vehicle leans to one side after parking
  • Harsh ride quality and clunking

How to Fix

Replace leaking air springs and the compressor if it has been overworked. All four springs should be inspected. Arnott aftermarket springs offer good value. The compressor relay should also be replaced preventively.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Arnott P-3258 X166 GLS AIRMATIC compressor with relay
    OEMArnott P-3258

    Confirmed failed compressor on an applicable 2017-2019 X166 GLS AIRMATIC vehicle after leak and power diagnosis Fitment/availability: The inspected direct U.S. Confirm VIN, X166 chassis and suspension option;

    ECS Tuning
  • Genuine Mercedes X167 GLS AIRMATIC compressor 1673209205
    OEMMercedes-Benz 1673209205

    Confirmed failed compressor on the cataloged X167 GLS450/GLS580 branch Fitment/availability: The inspected direct U.S. Confirm VIN, X167 suspension option and current supe

    FCP Euro
  • Arnott X166 rear AIRMATIC air spring 1663200325
    OEMArnott / Mercedes 1663200325

    Leak-confirmed rear air spring on the applicable X166 GLS standard-suspension branch Fitment/availability: The inspected GLS450 vehicle catalog links this direct Arnott product as 1663200325 and shows it in stock with price and purchase …

    FCP Euro
  • Arnott X167 rear AIRMATIC air spring 1673200025
    OEMArnott / Mercedes 1673200025

    Leak-confirmed rear air spring on the cataloged X167 GLS450/GLS580 branch Fitment/availability: The inspected GLS450 catalog links the direct Arnott 1673200025 product and explicitly catalogs GLS450/GLS580, with availability, price and p…

    FCP Euro

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • WarningThe GLS is heavier than the GLE and destroys air springs faster. Budget for air spring replacement every 60,000-80,000 miles as a cost of ownership.
Typical repair cost:$800 - $4,000

Research This Issue

Based on 1,500 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High Confidence1,500 owner reportsLast reported by owners Oct 2025Reviewed Mar 2026

On the 2017 Mercedes-Benz GLS, on the first-generation X166 GLS (2016-2017 GLS 350d, GLS 450, GLS 550, AMG GLS 63) and its GLE sibling, the main electrical connector on the electric steering rack was not sealed properly at the factory. Water wicks through the connector into the power-steering control unit, causing a short or signal loss that abruptly deactivates power assist - typically with a red steering warning and dramatically heavier steering, sometimes preceded by clunking at parking speeds. Failures have been reported well under 25,000 miles. This is the X166 counterpart to the later 22V-936 coupling recall and must not be confused with it.

Common Symptoms

  • Red 'Steering Malfunction' or 'Power steering failure' warning
  • Sudden heavy steering effort
  • Clunking from the steering rack at low speed
  • Intermittent assist that returns after restart

How to Fix

Free recall remedy under 17V-241: dealer replaces the connector, inspects the electric steering rack for water damage and replaces the rack when moisture is found. Outside the recall, a new electric steering rack on the X166 is $2,500-4,500 installed, so confirm campaign completion on any 2017 GLS and treat a 'Steering malfunction' message as a stop-driving event.

Typical repair cost:$0 - $4,500

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Sep 2026

On the 2017-2019 Mercedes-Benz GLS, the gasoline X166 GLS engines - M276 3.0 biturbo V6 (GLS 450), M278 4.7 biturbo V8 (GLS 550) and M157 5.5 biturbo V8 (AMG GLS 63) - share a well-documented failure where the seals inside the camshaft adjuster magnets (solenoids) and camshaft position sensors give up and pressurized oil is pushed into the sensor's electrical connector. From there the oil wicks along the wire strands into the main engine harness and can reach the ECU and other connectors. Early signs are oil in the cam-magnet plug and a wet valve-cover area; if ignored it produces cam-timing faults (P0016-family and P06DA-type codes), rough running and a harness or ECU replacement bill. MBWorld threads document dealers resealing solenoids under warranty and owners asking Mercedes for a campaign that was never issued.

Common Symptoms

  • Oil inside camshaft magnet or cam sensor electrical connector
  • Oil seeping at the front of the valve cover
  • Check engine light with camshaft correlation codes
  • Rough idle or misfire after oil reaches other connectors
  • Oil found inside ECU connector

How to Fix

Replace the leaking camshaft adjuster magnet(s) and/or cam sensor with the current revised part and, if any oil is in the connector, install the Mercedes harness-extension 'pigtail' repair sections so the contaminated section is cut out and the oil cannot migrate further. Check the connectors at every oil change on these engines. Solenoid plus pigtail is about $250-600 per position; if the harness or ECU is already saturated, $2,000-4,500. No recall or extended warranty exists.

Typical repair cost:$250 - $4,500

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Sep 2026

On the 2017-2019 Mercedes-Benz GLS OM642, the 2017-2019 X166 GLS 350d uses the OM642 V6 turbodiesel, not the OM656 inline-six fitted to the X167, and it inherits the OM642's signature fault: the two seals on the engine-oil cooler that sits at the bottom of the V between the cylinder banks harden from heat and leak. Mercedes switched from orange to purple Viton seals around 2010, but owner threads document even the Viton seals failing at 7-8 years/80-120k miles. Oil pools in the valley, drips onto the transmission bellhousing and exhaust, and is frequently misdiagnosed as a rear main or turbo leak. Adjacent turbo-pedestal gaskets and the oil filter housing are common secondary leak sources on the same job.

Common Symptoms

  • Oil drips from the bellhousing or under the engine toward the rear
  • Burning-oil smell after highway driving
  • Oil visible pooled in the engine valley under the intake
  • Slow oil loss with no external leak visible from above

How to Fix

Confirm with a dye test and a borescope into the valley. The fix is replacing the oil cooler seals with the current Viton parts (A6421880280 series) and while the intake is off, the turbo pedestal gasket, intake manifold seals and often the swirl-flap motor. It is a 8-12 hour labor job: $1,500-2,800 independent, $2,500-4,000 dealer. No recall applies.

Typical repair cost:$1,500 - $4,000

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
Medium ConfidenceVerifiedReviewed Sep 2026
Community reported
1,100 owners

On the 2017-2023 Mercedes-Benz GLS, the 9G-Tronic nine-speed automatic exhibits harsh low-speed shifts and hunting between gears on inclines. The transmission software struggles to select the optimal gear among nine ratios, particularly noticeable in stop-and-go traffic.

Common Symptoms

  • Jerky 1-2-3 shifts in city driving
  • Transmission hunts between gears on hills

How to Fix

Update the TCU software to the latest calibration at a Mercedes dealer. Perform a transmission adaptation reset after the update. A fluid and filter change can also improve shift quality.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Genuine Mercedes 725.0 transmission service kit 7252703707
    OEMMercedes-Benz 7252703707

    VIN-confirmed due fluid-and-filter service on the cataloged GLS450 725.0 branch after harsh-shift diagnosis Fitment/availability: The inspected FCP GLS450 transmission catalog links this direct genuine Mercedes 7252703707 service kit and…

    FCP Euro

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipAfter a TCU update, drive the vehicle in normal conditions for 200+ miles to allow the transmission to relearn your driving style. Shift quality improves significantly after the adaptation period.
Typical repair cost:$150 - $2,500

Research This Issue

Based on 1,100 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
Medium Confidence1,100 owner reportsLast reported by owners Sep 2025Reviewed Mar 2026
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Frequently Asked Questions

What are the most common Mercedes-Benz GLS problems?

According to Au7o's analysis of 2,600+ owner reports, the 2017 Mercedes-Benz GLS has 5 documented issues. The most frequently reported are: AIRMATIC Air Suspension Failure, Electric Power Steering Rack Connector Water Intrusion Causing Loss of Steering Assist (Recall 17V241), 9G-Tronic Harsh Shift. Of these, 2 are rated critical and should be addressed promptly.

Is the Mercedes-Benz GLS reliable?

The 2017 Mercedes-Benz GLS has 5 known issues documented across 2,600+ owner reports. 2 issues are rated critical: AIRMATIC Air Suspension Failure and Electric Power Steering Rack Connector Water Intrusion Causing Loss of Steering Assist (Recall 17V241). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Mercedes-Benz GLS problems?

Repair costs for known Mercedes-Benz GLS issues range from $0 to $4,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, AIRMATIC Air Suspension Failure, typically costs $800-$4,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2017-2023 Mercedes-Benz GLS AIRMATIC Air Suspension Failure?

The GLS AIRMATIC system is prone to air spring leaks and compressor failure due to the vehicle's heavy curb weight (5,700+ lbs). Front air springs tend to fail first. The compressor overworks to maintain ride height and eventually burns out. Repairs typically run $800-$4,000. Severity: high.

What is the 2017 Mercedes-Benz GLS Electric Power Steering Rack Connector Water Intrusion Causing Loss of Steering Assist (Recall 17V241)?

On the first-generation X166 GLS (2016-2017 GLS 350d, GLS 450, GLS 550, AMG GLS 63) and its GLE sibling, the main electrical connector on the electric steering rack was not sealed properly at the factory. Water wicks through the connector into the power-steering control unit, cau… Repairs typically run $0-$4,500. Severity: high.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data sourced from 2,600+ owner reports, NHTSA recalls, TSBs, and automotive forums.

FAQ

What is the 2017-2023 Mercedes-Benz GLS 9G-Tronic Harsh Shift?

The 9G-Tronic nine-speed automatic exhibits harsh low-speed shifts and hunting between gears on inclines. The transmission software struggles to select the optimal gear among nine ratios, particularly noticeable in stop-and-go traffic. Repairs typically run $150-$2,500. Severity: medium.

What is the 2017-2019 Mercedes-Benz GLS M276 / M278 / M157 Camshaft Adjuster Solenoid and Cam Sensor Oil Leak Wicking into Engine Wiring Harness?

The gasoline X166 GLS engines - M276 3.0 biturbo V6 (GLS 450), M278 4.7 biturbo V8 (GLS 550) and M157 5.5 biturbo V8 (AMG GLS 63) - share a well-documented failure where the seals inside the camshaft adjuster magnets (solenoids) and camshaft position sensors give up and pressuriz… Repairs typically run $250-$4,500. Severity: medium.

What is the 2017-2019 Mercedes-Benz GLS OM642 3.0 V6 Diesel Oil Cooler Seal Failure Leaking Oil into the Engine Valley (GLS 350d)?

The 2017-2019 X166 GLS 350d uses the OM642 V6 turbodiesel, not the OM656 inline-six fitted to the X167, and it inherits the OM642's signature fault: the two seals on the engine-oil cooler that sits at the bottom of the V between the cylinder banks harden from heat and leak. Merce… Repairs typically run $1,500-$4,000. Severity: medium.