The OM642 fuel filter housing comes in two versions — 3-pin and 5-pin — based on whether your van has an integrated fuel heater in the filter housing.
The 3-pin housing contains only the Water-in-Fuel (WIF) sensor. The 5-pin housing adds an electric heating element that warms diesel in cold weather to prevent fuel gelling.
How to check:Open the hood and locate the fuel filter housing on the driver's side near the firewall. Count the pins on the electrical connector. 3 pins = order the 3-pin kit. 5 pins = order the 5-pin kit. Year alone is not reliable — Mercedes built these for multiple markets.
Installing the wrong housing won't damage the engine, but a mismatched heater circuit will set fault codes and leave you without cold-weather protection.