DTC 323 — Engine Coolant Level Below Warning / Critical Level — International DT466E
DTC 323 on International DT466E (1996–2003) indicates the coolant level sensor reports low coolant. The ECM may warn, derate or shut down depending on…
What it means
Navistar three-digit code 323 means the coolant level sensor reports low coolant on the International DT466E. This is a Navistar flash code, not an OBD-II P-code.1
Most likely causes
- Low coolant from a leak or consumption — External or internal coolant loss reduces the level seen by the sensor. Typical on this platform: top up and look for leaks.1
- Failed or faulty coolant level sensor — A failed level sensor can set the code even with adequate coolant. Typical on this platform: a failed level sensor can also set it.1
- Wiring or connector fault to the coolant level sensor — Open or shorted signal/ground wiring to the sensor can cause a low-level indication.1
How to diagnose
- Verify the code with a Navistar scan tool or flash code read; DTC 111 = no faults.
- Inspect coolant level in the radiator and recovery tank when cold; top up if low and look for leaks.
- Inspect coolant level sensor and its connector for corrosion, damage, or loose connection.
- Check sensor wiring for opens/shorts to ground or power; repair as needed.
- If coolant is full and wiring is good, test/replace the coolant level sensor.
Parts and tools you may need
- Coolant (spec per manual)
- Coolant level sensor
- Basic hand tools
- Navistar scan tool or flash code reader
Tools you’ll need
- Navistar-compatible diagnostic scan tool — Reads Navistar flash code 323 and confirms active/inactive status on the DT466E.
- Digital multimeter — Checks sensor supply voltage, signal voltage, and wiring continuity for opens or shorts to ground/power.
- Coolant pressure tester — Pressurizes the cooling system to reveal external leaks causing low coolant that triggers code 323.
- Inspection mirror and flashlight — Allows visual inspection of the coolant level sensor, connector, and hard-to-see areas for corrosion or damage.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| Temperature or pressure sensor (coolant, intake air, oil, fuel temp) | $30–$150 | 0.3–1.5 hrs | Easy DIY |
| Coolant hose or leak repair | $20–$200 | 0.5–3 hrs | DIY with tools and a manual |
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 coolant loss is rapid, overheating occurs, or engine protection shutdown is active, have a qualified diesel technician inspect the cooling system promptly. Do not attempt high-pressure oil system repairs. This guide is diagnostic only.
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
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