Bosch 9778 Spark Plug - Exhaust Side

Bosch OE Fine Wire Iridium Spark Plug 9778

Bosch 9778 is an OE Fine Wire Iridium spark plug built for consistent ignition performance and extended service life. It uses an ultra-fine wire iridium center electrode, a platinum ground electrode tip, and a resistor design to support stable spark delivery in demanding secondary ignition systems.

Compatible With 2008-2010 Dodge Ram 1500, exhaust side; 2008-2010 Dodge Dakota, exhaust side; 2008-2009 Chrysler Aspen, exhaust side; 2008-2009 Dodge Durango, exhaust side; 2008-2009 Jeep Commander, exhaust side; 2008-2009 Jeep Grand Cherokee, exhaust side; 2011-2013 Ram 1500, exhaust side; and 2011 Ram Dakota, exhaust side. Bosch 9778 is also a direct OE-style choice for drivers searching for a Bosch spark plug for Ram 1500 exhaust side applications or a Bosch 9778 replacement for Jeep Grand Cherokee exhaust side fitment.

Key Features

• OE Fine Wire Iridium line from Bosch
• Iridium center electrode tip with fine wire design
• Platinum ground electrode tip with standard J-gap configuration
• Resistor spark plug with 5000 resistance
• 14 mm thread diameter, flat seat, and 26.5 mm reach
• Ceramic insulator with projected insulator type
• Heat range 8 and 1.25 pre-gap size
• Compatible with 4-cycle ignition systems

Detailed Description

Bosch OE Fine Wire Iridium spark plugs are engineered around OE spark plug technology, combining an iridium firing pin with a copper core and a platinum-tipped ground electrode. That construction supports reliable ignition performance, consistent combustion, and long service life in engines that call for a fine-wire iridium plug. The Bosch 9778 features a non-removable nut terminal, hex size 16, and a standard ground electrode tip design for straightforward OE-style replacement.

This plug is specified for exhaust side applications on select Ram, Dodge, Chrysler, and Jeep vehicles, including Ram 1500, Dakota, Durango, Aspen, Commander, and Grand Cherokee models from the listed years. If you are searching for Bosch 9778 for Ram 1500 exhaust side service or Bosch 9778 for Jeep Commander exhaust side replacement, this part matches the confirmed fitment data provided.

Common Issues This Part Can Address

• Misfire caused by worn or eroded spark plug electrodes
• Hard starting from weak or inconsistent spark output
• Rough idle related to degraded ignition performance
• Reduced throttle response from aging secondary ignition components
• Service intervals reached on OE-style iridium spark plugs

Installation Notes and Tips

Verify engine application, cylinder position, and exhaust-side fitment before installation. Check the specified gap and compare it to the pre-gap size listed for this plug before use. Inspect ignition coils, boots, and plug wells during service so the new spark plug is installed into a clean, dry ignition path.

Quality Assurance

Bosch builds the OE Fine Wire Iridium line to OE-level specifications using iridium and platinum electrode materials for durability and stable ignition performance. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.