NGK 9970 Diesel Glow Plug

NGK Diesel Glow Plug for Mercedes-Benz Diesel Engines

NGK Glow Plug 9970 is a diesel glow plug built for Mercedes-Benz applications that require OE-style cold-start performance and reliable combustion chamber heating. With ceramic-type construction, a 12-volt system rating, and a pin terminal design, this glow plug supports consistent starting in diesel engines across a wide range of Sprinter, E-Class, GL-Class, ML-Class, R-Class, and GLE models.

NGK’s long OE supply history and focus on original equipment standards make this part a direct-fit choice for drivers and technicians servicing Mercedes-Benz diesel starting systems. Part number 9970 is also referenced as CZ303.

Key Features

• Ceramic type diesel glow plug for fast heat-up characteristics
• 12-volt system voltage with 7.00 voltage specification
• Pin terminal design with M4 terminal thread size
• Flat seat type and 8 mm hex size for serviceability
• Thread diameter: 0.313 in.; overall length: 5.86 in.
• OE manufacturer application for Mercedes-Benz diesel engines
• Part number 9970 / CZ303

Fitment Coverage

• Fits 2022 Mercedes-Benz Sprinter 2500, N/A
• Fits 2022 Mercedes-Benz Sprinter 3500, N/A
• Fits 2021-2022 Mercedes-Benz Sprinter 3500XD, N/A
• Fits 2018 Mercedes-Benz Sprinter 3500XD, N/A
• Fits 2013-2021 Mercedes-Benz Sprinter 2500, N/A
• Fits 2013-2021 Mercedes-Benz Sprinter 3500, N/A
• Fits 2019-2020 Mercedes-Benz Sprinter 3500XD, N/A
• Fits 2016-2017 Mercedes-Benz GLE300d, N/A
• Fits 2014-2017 Mercedes-Benz Sprinter 2500, N/A
• Fits 2014-2017 Mercedes-Benz Sprinter 3500, N/A
• Fits 2014-2016 Mercedes-Benz E250, N/A
• Fits 2013-2015 Mercedes-Benz GLK250, N/A
• Fits 2015 Mercedes-Benz ML250, N/A
• Fits 2011-2013 Mercedes-Benz E350, N/A
• Fits 2010-2013 Mercedes-Benz R350, N/A
• Fits 2010-2012 Mercedes-Benz GL350, N/A
• Fits 2010-2011 Mercedes-Benz ML350, N/A
• Fits 2007-2009 Mercedes-Benz E320, N/A
• Fits 2007-2009 Mercedes-Benz GL320, N/A
• Fits 2007-2009 Mercedes-Benz ML320, N/A
• Fits 2007-2009 Mercedes-Benz R320, N/A

What This Glow Plug Helps Address

• Hard starting in cold weather diesel conditions
• Extended cranking before the engine fires
• Rough initial idle after startup
• Glow plug fault codes related to heating performance
• Uneven combustion during cold engine operation

Installation Notes and Tips

Verify the engine’s glow plug specification, terminal style, thread size, and overall length before installation. This part is listed for Mercedes-Benz diesel applications including Sprinter 2500, Sprinter 3500, Sprinter 3500XD, E250, E350, GL320, GL350, GLK250, GLE300d, ML250, ML320, ML350, R320, and R350 models in the years shown above. Use proper diesel service procedures and follow the vehicle manufacturer’s torque and diagnostic guidelines when replacing glow plugs.

This part cross-references Mercedes-Benz OE number A 001 159 66 01 for the same application.

Quality Assurance

NGK is a major OE supplier and manufacturer with decades of automotive ignition experience, and this glow plug reflects that OE-focused approach to fit, durability, and operational performance. Part number 9970 is built to meet original equipment standards for Mercedes-Benz diesel service.