2021 Mercedes-Benz GLS 450 Engine Problems
- Complaints
- 3about this part
- Share
- 10%of 31 total for the year
- Median mileage
- 11,000miles
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 3 complaints about the engine of the 2021 Mercedes-Benz GLS 450, 10% of the 31 complaints for this model year. Where a mileage was given, the median is 11,000 miles.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“On four occasions my car has stalled while in traffic very early in my ownership and then it happened again today with my family in the car and nearly caused an accident. The entire dash lights up with every warning when it happens. Sometimes the check engine light comes on after I shut the car off and restart it. My Mercedes dealer has had it in multiple times for this reason. The last time it was in for this (May of 2022) they reprogrammed the entire car. It happening again today has really made me lose a lot of faith in the vehicle, especially since we purchased it for the safety factors. …”
NHTSA complaint #11500946, filed 2023-01Related service bulletins
- 11038185Sep 26, 2026Complaint Sporadic warning message in instrument cluster "Engine oil pressure, stop switch off vehicle" (or similar) is shown in red on vehicles with low mileage. Cause…
- 11038176Sep 17, 2026Complaint Red coolant warning in instrument cluster. Fault codes U019F00 or U019F87 current/stored in MRG1 control unit. Cause Various causes Remedy Perform guided test for fault…
- 11028807Feb 14, 2026Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the engine control unit software does not correspond to current…
- 11026596Dec 6, 2025Complaint <p>ESP®, BAS, PRE-SAFE®, HOLD function, Hill-Start Assist, ESP® trailer stabilization, Adaptive Brake Lights, Lane Keeping Assist, Blind Spot Assist, Adaptive Brake…
- 11015545Mar 4, 2025Complaint Check engine light illuminated Fault code present in MRG3 control unit P22C800 or P22C900 - The valve of the exhaust gas turbocharger is jammed. Cause Check valve in…
- 11012056Dec 19, 2024Complaint Check engine light illuminated Fault code present in MRG3 control unit P22C900 - The valve of the exhaust gas turbocharger is jammed closed. Cause Check valve in charge…
- 11012055Dec 19, 2024Complaint Low engine oil level warning. Engine oil leak under vehicle. Cause Rear crankshaft radial seal rolled during installation Remedy -Check for external oil leak with…
- 11010744Nov 19, 2024Complaint Engine cooling fan running for an extended time after switching off vehicle. Cause Optimized thermal management in latest PTCU software. Remedy This is a normal…
- 11005347Jul 31, 2024Complaint Yellow coolant warning system message appears in instrument cluster. Fault code P048392 or P048397 present in N127 Powertrain Control Unit. Cause Faulty communication…
Engine: other model years
Other parts of the 2021 Mercedes-Benz GLS 450
14 complaintsOther or unknown
8 complaintsLane departure
3 complaintsForward collision avoidance
2 complaintsSeats
2 complaintsFuel system
1 complaintsSeat belts
1 complaintsSteering
1 complaintsBody and structure
1 complaintsTires
1 complaintsTransmission and drivetrain
1 complaintsVehicle speed control
1 complaints
← All problems reported for the 2021 Mercedes-Benz GLS 450
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology