If you have searched for A6421400687, you are probably trying to identify a Mercedes-Benz engine air pipe, intake pipe, or turbo/intercooler-related hose. The number appears in listings for several Mercedes vehicles fitted with the OM642 diesel engine. Parts sellers describe it using terms such as intake pipe, air pipe, air line, turbo hose, and intercooler pipe, so checking the exact application is important before ordering a replacement.
This guide explains what A6421400687 is, where it is used, what it does, signs that it may need attention, and how to check a replacement before buying it. Because Mercedes used the OM642 engine across several vehicle lines, the safest way to confirm fitment is to match the complete part number with the vehicle model, engine code, production details, and VIN.
What Is A6421400687?
A6421400687 is a Mercedes-Benz part number associated with an air-intake or forced-air system component used with certain OM642 diesel applications. Parts catalog and used-parts listings identify the number with air pipes, intake pipes, and turbo/intercooler hose descriptions. One listing, for example, identifies it as an original Mercedes intake pipe for W204 and W212 OM642 applications, while another lists it as a turbo/intercooler pipe for a W211 E-Class.
The different descriptions do not necessarily mean that every listing is referring to a different part. Used-car parts websites often describe the same component according to its position in the air system. This is why it is better to use the Mercedes part number and the vehicle details together rather than relying only on a seller’s title.
What Does A6421400687 Do?
The part forms part of the engine’s air path. In an OM642 diesel application, air needs to move through the intake and turbocharging system before reaching the engine. A properly fitted pipe or hose helps maintain the intended airflow and keeps connections between the relevant components sealed.
A damaged or poorly fitted air pipe can allow air to escape from the system or allow an unwanted leak into the intake path. Depending on the exact location and condition of the part, this can affect engine operation. The precise effect depends on the Mercedes model and the position of A6421400687 in that particular vehicle.
Which Mercedes Models Use A6421400687?
A6421400687 appears in parts listings for several Mercedes-Benz vehicles using OM642 diesel engines. Examples found in current parts databases and listings include the E-Class W211, CLS C219, ML W164, GL X164, R-Class W251, and CLK C209/A209. Some listings also show applications across different engine and production versions.
There are also listings connecting the part number with vehicles such as the W204 and W212. One current parts listing identifies A6421400687 for W204 and W212 OM642 applications, while another identifies it with a 2006 W211 E 280 CDI using engine code 642.920.
This does not mean that every OM642 Mercedes uses the same part. Production changes, engine versions, body styles, and component revisions can affect compatibility. Before purchasing, compare the number printed on the original component and confirm the application using the VIN or a Mercedes parts catalog.
Common Signs of a Faulty A6421400687
A problem with an intake or turbo-related pipe can show up in several ways. A visible crack, split, loose connection, damaged fitting, or other physical defect is one of the first things to check. Oil residue around an air connection can also be a reason to inspect the surrounding pipe and seals, although oil residue alone does not prove that A6421400687 has failed.
Drivers may also notice reduced acceleration, unusual air or hissing sounds, or changes in engine response when the turbocharger is working. A warning light or fault code can sometimes accompany an air-system problem. These symptoms are not exclusive to this part, however, so replacing A6421400687 based on one symptom alone can lead to unnecessary repairs.
If the vehicle has lost power or entered a reduced-power mode, a diagnostic scan and inspection of the complete intake and turbo system can help identify the actual cause. Other components can produce similar symptoms.
Why Does A6421400687 Fail?
Age and heat are common concerns for engine-bay air pipes and hoses. Repeated exposure to engine heat, vibration, pressure changes, and oil vapour can cause materials and connection points to deteriorate over time. A part that has been installed for many years may eventually develop cracks or lose its ability to maintain a proper seal.
Physical damage can also occur during engine work. A connector may not be seated correctly, a clamp may be loose, or a fitting can become damaged during removal. If a replacement part is installed without checking the surrounding connections, a leak may remain even after the old component has been changed.
The condition of a used part also deserves attention. Several current listings for A6421400687 are for used components, so buyers should inspect photographs and ask about cracks, fittings, seals, and the source vehicle before purchasing.
How to Check A6421400687
Start by locating the component and comparing its markings with the part number A6421400687. Look closely at the pipe, joints, clips, connectors, and mounting points. Signs of cracking, splitting, deformation, or a damaged connection should be investigated before the vehicle is returned to normal use.
A visual inspection should be followed by a proper diagnosis if the vehicle has performance problems. A mechanic can inspect the intake and turbocharging system for leaks and check whether the observed symptoms are actually connected to this component.
It is also worth checking the engine code and VIN. The OM642 engine was used in many Mercedes models, but the same engine family does not automatically mean that every pipe or hose is interchangeable. Parts databases themselves warn that vehicle production changes can affect fitment, making the original number and vehicle details important when buying a used component.
How to Replace A6421400687
The replacement process depends on the Mercedes model and the exact location of the component. In general, the old pipe is removed from its connected components, the mounting points and connectors are checked, and the replacement is installed in the same position.
Before fitting the new part, compare it with the old one. Check the shape, connection points, mounting locations, and part-number markings. This simple comparison can prevent problems caused by ordering a visually similar component that belongs to another version of the engine or vehicle.
After installation, the connections should be checked carefully. The engine should then be inspected for air leaks or abnormal sounds. If the vehicle originally had a warning light, fault code, or loss of power, further diagnostic work may be needed after the physical repair.
How Much Does A6421400687 Cost?
The price of A6421400687 depends on whether you choose a genuine used Mercedes component, an aftermarket replacement, or another available option. Used-parts listings can vary considerably because the condition, source vehicle, mileage, seller, and included fittings are not always the same.
For example, current listings show A6421400687 being sold as a used component from vehicles including the W211 E-Class and other OM642-powered Mercedes models. One German parts seller currently lists an original used intake pipe, while other marketplaces list used turbo/intercooler or intake-related versions.
Shipping can also make a noticeable difference to the final cost. For that reason, compare the total delivered price rather than looking only at the listed part price. More importantly, confirm fitment before paying, because a cheaper part that does not match your vehicle can create additional return and installation costs.
How to Choose the Correct Replacement
The first step is to confirm that A6421400687 is the number on your original component or in the parts information for your vehicle. Some sellers display the number with spaces as A 642 140 06 87, while others use 6421400687 without the letter or spaces. These formats can refer to the same Mercedes part number in listings.
Next, check the vehicle details. Include the Mercedes model, chassis or body code, engine code, production year, and VIN when possible. A listing may mention the same general model but still apply only to a particular engine or production range.
Finally, compare photographs when buying a used part. Check the shape and connection points against your existing component. One parts database specifically advises buyers to compare the part number and product images because changes during a vehicle’s production period can affect compatibility.
FAQs About A6421400687
What is A6421400687?
A6421400687 is a Mercedes-Benz part number associated with an air-intake, air pipe, or turbo/intercooler-related component on certain OM642 diesel applications. Sellers may use different descriptions for the same part, so the vehicle application should be checked before purchase.
Which Mercedes vehicles use A6421400687?
Listings connect the number with several Mercedes models, including the E-Class W211, CLS C219, ML
