DTC 313 — Engine Oil Pressure Below Warning Level — International DT466E

Engine oil pressure has dropped below the warning threshold on the International DT466E (1996–2003). The ECM can warn, derate or shut down for low oil pressure…

Updated October 15, 2026

What it means

Engine oil pressure has dropped below the warning level. On the DT466E this is a Navistar three-digit code read by flash codes or scan tool; it is not an OBD-II P-code. The ECM may warn, derate or shut down for low oil pressure depending on programming.¹

Most likely causes

1. Low engine oil level or oil loss — Low oil level reduces pump pickup and pressure. Check level on dipstick, inspect for external leaks, and confirm proper oil grade/viscosity for ambient temperature.¹
2. Actual low oil pressure due to engine wear or lubrication fault — Worn bearings, oil pump wear, or a clogged pickup screen can cause real low pressure. Verify with a mechanical gauge at idle and at speed before condemning the sensor.¹
3. Faulty engine oil pressure sensor or wiring — A failing EOP sensor or wiring can report low pressure. Compare sensor voltage to spec and check reference/ground circuits; sensor-circuit faults are distinct from real pressure loss.¹
4. Aerated or contaminated oil — Foaming or diluted oil reduces effective pressure. Check for coolant in oil, fuel dilution, or overfilled crankcase causing aeration.¹

How to diagnose

1. Confirm the code with a scan tool or flash code read; note if DTC 314 (critical level) also sets.
2. Check engine oil level on level ground with engine off; top up if low and inspect for leaks.
3. Install a mechanical oil pressure gauge to verify actual pressure at idle and at rated speed; compare to spec.
4. Inspect EOP sensor connector and wiring for corrosion, oil intrusion, or damage; check 5 V reference and ground integrity.
5. Review recent service history for oil change, filter, or oil type changes that could affect pressure.
6. If pressure is low on the mechanical gauge, investigate oil pump, pickup tube, bearing clearances, and oil condition before replacing sensors.
7. Clear codes, run engine to normal operating temperature, and recheck for recurrence of DTC 313.
8. If pressure is normal mechanically but code returns, test/replace the EOP sensor and repair wiring as needed.

Parts and tools you may need

• Mechanical oil pressure gauge with appropriate adapter
• Scan tool capable of Navistar three-digit codes
• Basic hand tools for sensor access
• Multimeter for sensor voltage checks
• Oil and filter for service if needed

Tools you’ll need

• digital multimeter — Checks 5 V reference, ground, and signal voltage at the EOP sensor connector to rule out wiring faults causing DTC 313.
• mechanical oil pressure gauge — Verifies actual engine oil pressure at idle and rated speed against spec to confirm if low pressure is real or sensor-related.
• heavy-duty diagnostic scan tool — Reads and clears Navistar DT466E flash codes like DTC 313/314 and monitors live oil pressure data during testing.
• oil pressure test kit — Provides adapters and hoses to safely connect a mechanical gauge to the DT466E engine oil gallery for accurate pressure measurement.

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

Stop the engine if oil pressure is critically low or the engine is noisy. Have a qualified diesel technician verify pressure mechanically and inspect internal lubrication components before continued operation.

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