Common Rail Control Valve Assembly F00RJ01704 for Injector 0445120110 0445120120 0445120156 0445120160 0445120164 0445120165 0445120225

A common rail pressure relief valve (CRPRV) is a mechanism in diesel engines that regulates fuel pressure in cars that use the common rail system for fuel injection. The CRPRV prevents fuel pressure spikes in the common rail. It is a small part that, if faulty, causes performance and diagnostic issues.

Wear and tear, contamination from particles and debris, and overpressure can cause the CRPRV to become faulty. While wear and contamination are straightforward concepts, you might wonder what overpressure is.

Overpressure in CRDI occurs when systems designed for a particular PSI exceed the set limit, forcing the CRPRV open. Let us use the example of a CRDI designed to handle fuel injection at 23000 PSI. If fuel pressure increases to 26000 PSI, there is a high chance the CRPRV forces open and releases that excess pressure into the return system.

The CRPRV functions to handle such cases of overpressure, but it cannot manage such situations many times without wear. At most, the CRPRV can handle one or two instances of overpressure before it gets soggy and forces open at even lower PSIs than the CRDI's spec.

Using our example, if overpressure, wear, or contamination weakens the CRPRV, fuel pressure lower than the 23000 PSI the system should handle might force open the valve.

Detecting overpressure, wear, or contamination is only possible via physical inspection or a diagnostic tool. Yet, some symptoms and signs could suggest a potential issue with the CRPRV in your car's engine. We discuss them below.