Mercedes-Benz GLE 400d W167

The OM656 shares the valve train weakness documented across Mercedes' new-generation diesel engines (OM654 and OM656). The roller-type rocker arms, particularly on the exhaust side, lose lubrication at the contact surface with the camshaft lobes. Early symptoms include a deep ticking or rumble audible through the air filter box at idle. Mercedes specialist workshops report this as one of their most frequent repairs on these engines. If caught early, replacing rocker arms and hydraulic tappets costs approximately 1,500-2,000 euro (parts around 500-700 euro, labor 6-8 hours). If the worn rockers have scored the camshaft lobes, camshaft and bearing housing replacement pushes the bill to 3,000-4,000 euro. Failures typically appear between 100,000-180,000 km, with 2019-2020 production engines more commonly affected. Mercedes has released updated rocker arm part numbers. Using premium oil and maintaining strict oil change intervals (every 15,000 km or annually, whichever comes first) helps delay onset.

The GLE 400d uses a 48V mild hybrid system (EQ Boost) with a small lithium-ion battery. Early 2020-2021 models are particularly affected by premature failures. The battery can die while the car is parked, leaving the vehicle unable to start and often unable to be jump-started normally. Mercedes issued Technical Service Bulletins addressing this issue, citing a painted ground contact point and defective battery units as root causes. A class-action lawsuit was filed in the US over this problem. An updated battery part number was released. Replacement typically costs 800-2,500 euro depending on whether a dealer or independent shop performs the work. The conventional 12V battery can also drain within 10-14 days if the car sits unused.

Many GLE W167 models are equipped with optional AIRMATIC air suspension. The rubber air springs become brittle with age and develop cracks, allowing air to escape. Symptoms include one corner sitting lower after overnight parking, or the compressor running excessively to compensate. A single OEM air strut costs approximately 800-1,200 euro per corner, with aftermarket alternatives from suppliers like Arnott available for 400-800 euro. The compressor can fail from overwork at an additional 600-1,000 euro. Cars with standard steel spring suspension avoid this issue entirely. Check for ride height adjustment controls in the centre console to identify AIRMATIC-equipped cars. Both sides of an axle should ideally be replaced simultaneously.

The GLE 400d has NOx sensors in the exhaust system as part of the SCR emissions treatment. These sensors are exposed to extreme heat and can degrade, triggering a 'No restart in X km' countdown warning on the dashboard. A single NOx sensor costs approximately 350-500 euro including fitting. Condensation in the exhaust can also damage them; Mercedes has recommended drilling a drain hole in the exhaust as a remedy in some cases. AdBlue injector or metering valve replacement costs 300-600 euro. Crystallization of AdBlue around the tank float sensor is another common issue, sometimes resolved by draining and refilling with fresh branded AdBlue. In worst cases, the complete AdBlue tank and pump assembly needs replacing at 1,500-2,000 euro. Cars that sit unused for long periods or predominantly do short trips are more susceptible.

Mercedes recalled approximately 800,000 OM654 and OM656 diesel vehicles (built January 2017 to October 2021) for a potential fire risk. Coolant can leak from the coolant pump into the vacuum system via a faulty seal. If coolant contacts certain electrical switch valves, an electrochemical reaction can cause overheating and potentially a fire. The recall applies directly to the GLE 400d. If the recall work has been completed (free at any Mercedes dealer), the cost is zero. If the vehicle somehow missed the recall and the pump fails outside coverage, replacement costs approximately 500-800 euro. This is a safety-critical issue: verify completion via VIN before purchase.

The OM656's twin-turbo setup uses a vacuum-operated actuator on the variable-geometry turbocharger. On some 2019-2020 models, the vacuum hose running near the DPF was insufficiently heat-shielded, causing it to soften and collapse. This prevents the turbo actuator from responding correctly, leading to transmission judder during gear changes and reduced power. Standard diagnostics may not detect the collapsed hose directly, making diagnosis difficult. One documented case took nearly two years and multiple dealer visits to resolve. Mercedes developed a heat shield and insulation wrap as a permanent fix. If caught under warranty, the repair is free. Out of warranty, hose replacement with the updated heat shield costs approximately 300-600 euro. If the actuator itself is damaged from prolonged malfunction, turbo work can reach 1,200-1,500 euro.

Some GLE 400d owners report jerky shifting from the 9G-Tronic transmission, especially during cold starts or in urban traffic. Common causes include valve body calibration drift, sticky solenoids, or degraded fluid. In many cases, a software update at the dealer resolves the issue at no cost or minimal cost. A transmission fluid change (recommended every 60,000-80,000 km despite some marketing describing it as a lifetime fill) can also improve shift quality. If the valve body requires replacement, costs can reach 1,500-2,500 euro including labor. The jerkiness at low speeds appears to be somewhat inherent to the 9G-Tronic design and may not be fully eliminated.

The MBUX infotainment system can occasionally fail to start, presenting a completely black centre screen. When this occurs, navigation, reversing cameras, and audio are all unavailable. NHTSA issued recall 21V354 for 2019-2021 GLE models where MBUX software could fail to start. A dealer-applied or over-the-air software update resolves most cases at no cost. In some instances, the MBUX head unit needs replacement (located under the passenger seat), costing 800-1,200 euro. Other reported issues include CarPlay disconnections, voice control failures, and occasional mid-drive freezes. A 10-second press of the power button performs a hard reset as a temporary workaround.