DTC 333 — Injection Control Pressure Above / Below Desired Level — International DT466E

Diagnostic guide for Navistar DTC 333 on International DT466E (1996–2003).

Updated October 15, 2026

What it means

DTC 333 is set when measured injection control pressure is not following the ECM’s desired pressure on the DT466E HEUI system.¹

Most likely causes

1. High-pressure oil leak in the HEUI system (injector O-rings, standpipes, dummy plugs, high-pressure oil lines, or high-pressure oil pump seals) causing ICP to fall below desired. — Leaks reduce the oil volume the pump can maintain, so actual ICP deviates low from commanded.¹²³
2. Sticking or failing injection pressure regulator (IPR) valve causing ICP to be above or below desired. — A stuck IPR can over-pressurize or under-pressurize the high-pressure oil circuit.¹⁴
3. Low or aerated engine oil (low level, wrong viscosity, or air ingestion) reducing ICP control. — Insufficient or aerated oil prevents the high-pressure pump from building stable ICP.¹³
4. Worn high-pressure oil pump unable to generate required ICP. — Pump wear limits maximum ICP, so pressure cannot track desired under load.¹²
5. Faulty ICP sensor or wiring giving incorrect pressure feedback to the ECM. — Erroneous sensor readings make actual pressure appear out of range even if hydraulic pressure is correct.⁴

How to diagnose

1. Verify the code with a scan tool and note freeze-frame conditions (engine speed, load, oil temperature).
2. Check engine oil level and condition; look for aeration, contamination, or incorrect viscosity.
3. Inspect high-pressure oil system components for external leaks, damaged fittings, and signs of oil weep at injectors and pump.
4. Command IPR duty cycle with a scan tool and monitor ICP actual vs desired; look for deviation at idle and under load.
5. Perform a high-pressure oil leak test (e.g., monitor ICP during cranking and at idle) to identify internal leakage.
6. Check ICP sensor voltage and compare to a known-good reference or substitute sensor to rule out sensor drift.
7. Inspect IPR valve operation and connector; check for sticking, debris, or electrical faults.
8. If pressure cannot be built during cranking, suspect large high-pressure oil leak, IPR, low oil, or pump failure.

Parts and tools you may need

• Scan tool capable of reading Navistar three-digit codes and live ICP/IPR data
• Mechanical oil pressure gauge
• High-pressure oil test fittings and pressure gauge
• Basic hand tools and inspection light
• Replacement ICP sensor, IPR valve, high-pressure oil O-rings/seals as needed

Tools you’ll need

• OBD-II scan tool — Reads DTC 333 and displays ICP actual vs desired plus IPR duty cycle for commanded pressure tests.
• digital multimeter — Checks ICP sensor voltage and IPR valve electrical continuity to rule out sensor or wiring faults.
• high-pressure oil leak test kit — Monitors ICP during cranking and idle to quantify internal HEUI leaks causing pressure deviation.
• engine oil pressure gauge — Verifies base engine oil pressure and detects aeration or low oil conditions affecting HEUI pressure control.

Rough cost and difficulty

Typical US independent-shop figures; labor runs about $140–$200 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If the engine exhibits hard/no start, severe power loss, or repeated DTC 333 after basic checks, have a qualified diesel technician perform pressure testing and internal inspection of the HEUI system. Do not service high-pressure oil components without proper training and safety precautions.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources