21010372 Volvo FH12 D12C Overflow Valve

What does an overflow valve do?

The injector pump overflow valve is a critical control component that maintains constant internal pump pressure by redirecting excess fuel back to the return line. This component is essential for ensuring stable engine operation, as it directly impacts idle stability and fuel consumption levels in heavy commercial vehicle engines.

Vehicle and engine compatibility

This specific component is fitted to Volvo FH12 trucks equipped with D12C engines. It serves as a reliable replacement for original components, ensuring the fuel system operates within specified pressure tolerances to prevent performance loss.

Installation and maintenance

For proper installation, technicians should ensure the M10x1 thread is clean and free of debris. Because air or contaminants entering the fuel system can cause serious faults, it is recommended that an experienced workshop performs the replacement and ensures the system is correctly bled of air after installation.

Troubleshooting guidance

If engine performance fluctuates or fuel consumption increases unexpectedly, inspecting the overflow valve is a necessary step in troubleshooting the injection pump system.

OE cross-reference

0103 064 (Injector Pump Overflow Valve) is the equivalent of the Volvo OE number. This part directly replaces Volvo OE number 21010372.