DTC 335 — ICP Unable to Build Pressure During Cranking — International DT466E

Diagnostic reference for International DT466E (1996–2003) Navistar three-digit code 335.

Updated October 15, 2026

What it means

Injection control pressure does not build while cranking. On the DT466E HEUI system this is a classic crank-no-start condition where the ECM commands pressure but the high-pressure oil side cannot generate enough ICP to fire the unit injectors.¹

Most likely causes

1. Large high-pressure oil leak in the HEUI system — External or internal leakage from the high-pressure oil pump, injector O-rings, branch tubes, standpipes, or the high-pressure oil rail prevents ICP from rising during cranking.¹
2. Injection pressure regulator (IPR) valve stuck open or failing — The IPR cannot close to build pressure, so ICP remains low during cranking.¹
3. Low engine oil level or aerated oil — Insufficient oil volume or air ingestion reduces the high-pressure oil pump’s ability to generate ICP.¹
4. Failed high-pressure oil pump — A worn or damaged high-pressure oil pump cannot produce the required ICP while cranking.¹

How to diagnose

1. Verify the code is present and active with a scan tool or flash code read; confirm engine cranks normally and there is no CMP fault present.
2. Check engine oil level and condition; look for signs of aeration, contamination, or recent oil loss.
3. Inspect high-pressure oil system for external leaks at the pump, fittings, branch tubes, and injector connections; note oil weeping that would bleed pressure during cranking.
4. Monitor ICP sensor voltage/pressure with a scan tool while cranking; confirm pressure stays near zero and does not rise with cranking.
5. Command IPR duty cycle with a scan tool and observe ICP response; a lack of pressure rise suggests IPR stuck open, pump failure, or a large leak.
6. Inspect IPR valve connector and wiring for damage or corrosion; check IPR screen for debris that could hold the valve open.
7. If oil level and external leaks are normal, perform a high-pressure oil system leak test using approved diagnostic procedures to isolate internal leaks at injectors or standpipes.

Parts and tools you may need

• Scan tool capable of reading Navistar three-digit flash codes and live ICP/IPR data
• Digital multimeter
• Inspection light and mirrors
• Clean shop towels
• Approved high-pressure oil system test equipment

Tools you’ll need

• OBD-II scan tool — Reads active DTC 335 and displays live ICP pressure and IPR duty cycle while cranking to confirm pressure does not build.
• digital multimeter — Checks IPR valve connector voltage and continuity to rule out wiring faults that could keep the regulator stuck open.
• mechanical oil pressure gauge — Verifies base engine oil pressure during cranking to ensure the HEUI pump has adequate supply before high-pressure testing.
• high-pressure oil leak test kit — Isolates internal HEUI leaks at injectors, standpipes, and branch tubes that bleed ICP during cranking.

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

High-pressure oil systems operate at very high pressures. If diagnosis points to internal high-pressure oil leaks, pump failure, or IPR service, have a qualified diesel technician perform testing and repair. Do not attempt step-by-step repair of high-pressure oil injection components. If the engine does not start after basic checks, seek professional diagnosis promptly.

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