This manual covers the Volvo B21 Engine, an internal combustion, liquid-cooled inline-4 engine with a displacement of 2.1 liters (2100cc) and fuel injection. Designed for reliability and performance, the B21 engine has been a cornerstone of Volvo's engineering, offering robust construction and efficient operation suitable for a wide range of applications. Its enduring design reflects a commitment to quality and longevity, making it a dependable choice for various automotive needs. This comprehensive service and repair manual provides detailed guidance for maintaining and troubleshooting the Volvo B21 engine. It includes essential information on general maintenance, periodic lubrication, and in-depth repair procedures for critical systems such as the engine, transmission, electrical system, chassis, body, suspension, brakes, steering, fuel system, emission system, engine control system, and restraint system. With clear instructions and included wiring diagrams, this manual is an indispensable resource for owners, mechanics, and technicians seeking to ensure the optimal performance and longevity of their Volvo B21 engine.