2019 Mercedes-Benz GLS 3.0L Diesel · S44 LBM

Every X167 GLS rides on air springs, either AIRMATIC or E-Active Body Control. Specialist reliability data identifies cracked rubber bellows as the most common failure - one corner sags after the car has stood, and if it is ignored the compressor runs continuously trying to hold pressure and burns out, turning a single-strut job into a compressor plus strut bill. The same source notes a Mercedes technical bulletin for an 'AIRMATIC fault' warning caused by control-unit software rather than a mechanical leak, so a swap of struts may not clear it. Parkers confirms air suspension is standard across the range, which means no GLS escapes the cost.

DVSA campaign R/2024/173 covers 218 UK GLS cars because the 48V ground connection under the passenger seat could come loose, with the bolts to be checked and re-torqued. Overseas recall data for the same 167 platform is more blunt: a manufacturing defect left the threaded nut securing the 48V harness under the seat inadequately torqued, and a loose connection can overheat, causing a fire risk plus widespread electrical faults on GLE and GLS cars built 2019-2022. Owners also report sudden '48V battery malfunction' warnings, loss of stop-start and a no-start that a conventional jump lead will not fix.

The GLS 400d runs the OM656 six-cylinder diesel with a full SCR system. Specialist reliability data warns that urban use prevents the particulate filter completing regeneration, producing warning lights, reduced power and eventually limp mode, with a blocked DPF that cannot be cleaned in situ running to a full replacement. Mercedes specialists describe the companion emissions failure pattern: an AdBlue warning, then a countdown stating the engine will not restart, usually caused by a failed dosing pump, tank heater or NOx sensor rather than low fluid level. Heavy SUVs used for school runs are the worst cases.