Mercedes Sprinter Glow Plug Control Unit – OEM | OM642 3.0L V6 | #6429001402 (2010–2022)

DESCRIPTION:

The glow plug control unit is one of the most overlooked causes of hard cold starts and glow plug fault codes on the OM642 Sprinter — and one of the most common reasons freshly replaced glow plugs fail prematurely. This OEM controller manages the timing and power delivery to all six glow plugs and is a known failure item on high-mileage NCV3 and VS30 Sprinters. Replacing it alongside a full glow plug service is the right way to do the job once and do it right.

What This Part Does

The glow plug control unit (also referred to as the preheating output stage or glow plug relay module) receives instructions from the engine ECU and controls when and how long each glow plug is energized before and after cold starts. It manages pre-glow, after-glow, and diagnostic functions for the entire glow plug circuit. A failed or failing control unit causes uneven power delivery to the plugs — leading to hard starts, fault codes, and accelerated glow plug wear even on a freshly installed set.

Common Symptoms of a Failing Glow Plug Control Unit

• Hard starting in cold weather despite new glow plugs
• Check engine light with P0670 (glow plug control circuit) or individual cylinder glow plug codes (P0671–P0676)
• Glow plug warning light on the instrument cluster
• Repeated glow plug failures shortly after replacement

Why Replace It With the Glow Plugs

A faulty control unit sends incorrect voltage or timing signals to the plugs — burning them out prematurely. If you're replacing glow plugs without inspecting or replacing the control unit, you're likely creating the conditions for the same failure to repeat. This is the current supersession part number, replacing multiple earlier versions of the unit.

Fitment

• 2010–2022 Mercedes-Benz Sprinter 2500 – 3.0L V6 Diesel (OM642)
• 2010–2022 Mercedes-Benz Sprinter 3500 – 3.0L V6 Diesel (OM642)
• 2018–2022 Mercedes-Benz Sprinter 3500XD – 3.0L V6 Diesel (OM642)
• 2010–2017 Freightliner Sprinter 2500/3500 – 3.0L V6 Diesel (OM642)

Always verify your VIN before ordering. Contact us and we'll confirm fitment before you buy.

Part Numbers

• Mercedes OEM: 6429001402 / A6429001402 / 642-900-14-02
• Supersedes: 6429007801, 6429005801, 6429002800, 6421532079, 6421531979