Diesel Trouble Codes

Rough Running or Misfire — International DT466E

A DT466E that runs rough or misfires usually shows a single-cylinder contribution problem or unstable injection control pressure affecting all cylinders.

Updated October 15, 2026

What’s going on

On the International DT466E (1996-2003) rough running or misfire typically points to one cylinder with a weak injector or injector circuit fault, or to unstable injection control pressure that affects all cylinders. A miss usually points to one cylinder: a weak injector or an injector circuit fault (cylinder contribution and injector circuit codes), or unstable injection control pressure affecting all cylinders.1

Most likely causes

  1. Weak or failing HEUI injector on one cylinder — A single-cylinder contribution failure can set DTC 461 (cylinder 1) and similar codes for other cylinders. A weak injector, injector circuit fault or a mechanical/compression problem on that cylinder; DTC 462-466 are cylinders 2-6.21
  2. Injector circuit open or driver fault — An open between high and low side on a cylinder injector circuit can set DTC 421 for cylinder 1; DTC 422-426 are cylinders 2-6. The ECM can also detect a fault in the injector driver circuitry, DTC 525.34
  3. Injection control pressure not following desired — Measured injection control pressure is not following the ECM’s desired pressure, DTC 333. High-pressure oil leaks, a sticking IPR valve, low or aerated oil, or a worn high-pressure oil pump; causes low power, rough running or stalling. A miss on the DT466E usually points to one cylinder: a weak injector or an injector circuit fault (cylinder contribution and injector circuit codes), or unstable injection control pressure affecting all cylinders.51

How to narrow it down

  1. Read stored Navistar three-digit DTCs with a scan tool or flash codes; note DTC 461, 421, 525, 333 if present.
  2. Check engine oil level, condition and for aeration; verify oil meets spec because HEUI injection uses high-pressure engine oil for injection control pressure.
  3. Inspect injector harness and connectors for chafing, corrosion or loose pins; pay attention to the two injector banks driven by high-side/low-side circuits.
  4. Monitor injection control pressure actual vs desired at idle and under load; look for DTC 333 conditions where pressure is above/below desired.
  5. Perform a cylinder contribution test to identify a weak cylinder; a failed contribution can set DTC 461 for cylinder 1.
  6. Inspect high-pressure oil system components for leaks (standpipe, dummy plugs, O-rings, injector O-rings) and check IPR valve operation; low ICP causes rough running.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
Wiring or connector repair$10–$1001–4 hrsDIY with tools and a manual
IPR (injection pressure regulator) valve$70–$3000.5–2 hrsDIY with tools and a manual
Fuel injector (each)$250–$5001.5–3 hrsShop
High-pressure oil pump (HPOP)$1,000–$1,4003–6 hrsShop

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 high-pressure oil leaks are suspected, or injector replacement or ECM driver diagnosis is needed, have a qualified diesel technician perform the work. Do not service high-pressure oil components without proper training and safety precautions. If the engine shows metal contamination, loss of oil pressure, or repeated injector circuit codes, professional diagnosis is advised. This guide is for diagnostic direction only. Repair of safety-critical systems should be performed by a qualified professional.

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

  1. Curated symptom seed — International DT466E (curated) ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — International DT466E (curated) ↩︎

  3. Curated DTC seed — International DT466E (curated) ↩︎

  4. Curated DTC seed — International DT466E (curated) ↩︎

  5. Curated DTC seed — International DT466E (curated) ↩︎