CUMMINS 3957290 OEM INJECTOR RETURN CHECK VALVE – RAM 5.9L (2003–2007)

Product Description

CUMMINS 3957290 OEM INJECTOR RETURN CHECK VALVE – RAM 5.9L (2003–2007) is the genuine rear-of-head injector return check valve your 5.9L Cummins depends on to hold proper return pressure, prevent backflow, and stop those annoying fuel leaks at the back of the cylinder head. This OEM Cummins valve is a direct replacement for the factory part and is also used on many Tier 3 ISC/ISL industrial applications when verified by ESN.

Key Features & Benefits

• Genuine Cummins OEM check valve for consistent injector return pressure and proper fuel system operation.
• Direct-fit replacement located at the rear of the cylinder head on the injector return banjo fitting.
• Helps cure fuel seepage, fuel odor, soft prime conditions, and hard hot-starts caused by a worn return check valve.
• Built to Cummins specifications for long service life and leak-free sealing.
• One valve required per engine; sold individually.

Fitment

• Automotive: 2003–2007 Dodge Ram 2500/3500 with 5.9L ISB 24V common-rail Cummins (rear of cylinder head on injector return line).
• Industrial / Off-Highway: Commonly used on Tier 3 ISC/ISL 8.3L/8.9L Cummins applications (verify by Engine Serial Number before ordering).

Location & Function

• Location: Back of the cylinder head on the injector return line banjo fitting.
• Function: Maintains correct injector return pressure and prevents fuel from draining back, protecting injector performance and hot-start behavior.

What’s Included

• (1) Genuine Cummins Injector Return Check Valve – Part #3957290.
• Sealing washers and return line hardware sold separately (see related Cummins parts below).

Recommended Cummins Companion Parts (Cross-Reference & Related)

• Rear injector feed tube for #6 cylinder (common-rail 5.9L):
  CUMMINS 4988806 OEM INJECTOR FUEL SUPPLY TUBE (#6) – RAM 5.9L (2003–2007)
• Earlier 12-valve fuel return check valve (for 1989–1998 5.9L):
  CUMMINS 3924726 OEM FUEL RETURN CHECK VALVE – RAM 5.9L 12V (1989–1998)
• 12-valve injector return line assembly (if updating an older platform in the fleet):
  CUMMINS 3926103 OEM FUEL INJECTOR RETURN LINE – RAM 5.9L 12-VALVE (1994–1998)
• Common-rail fuel rail pressure relief valve (PRV) for 2003–2007 5.9L:
  CUMMINS 3947799 OEM FUEL RAIL PRESSURE RELIEF VALVE (PRV) – RAM 5.9L (2003–2007)
• Engine oil dipstick for 2003–2007 5.9L Cummins:
  CUMMINS 3959009 OEM ENGINE OIL DIPSTICK – RAM 5.9L (2003–2007)
• Aftermarket Cross-Reference (Identification Only): PAI 042212 fuel check valve (barcoded 193807183981) – used here as a cross-reference number for fleets and parts managers.

Installation Notes

• Always replace the sealing washers during service (one 12mm and one 14mm banjo washer per connection, sold separately).
• Clean all mating surfaces and inspect the injector return line for cracking, abrasion, or corrosion.
• Torque fasteners to the factory specification and prime the fuel system before startup.
• After installation, run the engine to operating temperature and re-check for leaks at the rear of the cylinder head.

FAQ

WILL THIS VALVE FIT MY 2003–2007 5.9L CUMMINS RAM?
Yes. This is the correct injector return check valve for 2003–2007 Ram 2500/3500 trucks equipped with the 5.9L ISB 24V common-rail Cummins. Always confirm by VIN or Engine Serial Number if you are unsure.

WHERE IS THE 3957290 CHECK VALVE LOCATED?
It mounts at the rear of the cylinder head on the injector return line banjo fitting. If you see fuel seepage or staining at the back of the head, this is a key inspection point.

WHAT SYMPTOMS POINT TO A BAD INJECTOR RETURN CHECK VALVE?
Common symptoms include diesel fuel leakage at the back of the head, a persistent fuel odor, soft or slow system prime after sitting, and hard hot-starts from fuel draining back through a worn check valve.

IS THIS A GENUINE CUMMINS PART OR AFTERMARKET?
This part number 3957290 is a genuine Cummins OEM check valve supplied by CPP Diesel. Aftermarket numbers like PAI 042212 are listed only as cross-reference identifiers for parts managers and catalog matching.

DOES THIS VALVE FIT INDUSTRIAL CUMMINS ENGINES?
Yes, Cummins uses 3957290 on many Tier 3 ISC/ISL and other industrial/medium-duty applications. However, you must verify by Engine Serial Number (ESN) and parts catalog before ordering for non-automotive equipment.

WHAT ELSE SHOULD I REPLACE WHILE I’M THERE?
At minimum, replace both sealing washers. Many technicians also renew the injector feed tube for #6 cylinder, inspect or replace the rear return line, and confirm the fuel rail pressure relief valve is in good condition for a complete, leak-free repair.

Specifications for cummins 3957290