Diesel Trouble Codes

DTC 461 — Cylinder 1 – Cylinder Contribution Test Failed — International DT466E

Diagnostic guide for International DT466E (1996–2003) Navistar three-digit code 461.

Updated October 15, 2026

What it means

Cylinder 1 failed the cylinder contribution test. On the DT466E this is a Navistar three-digit code indicating cylinder 1 is not contributing as expected during the ECM’s contribution test. DTC 462-466 are cylinders 2-6.1

Most likely causes

  1. Weak or failing HEUI injector on cylinder 1 — Injector spray pattern or control oil sealing degraded, causing reduced contribution on cylinder 1.1
  2. Injector circuit fault on cylinder 1 (high-side/low-side open or driver issue) — Open or high resistance in cylinder 1 injector coil, connector or harness, or an injector driver fault affecting that cylinder.123
  3. Mechanical/compression problem on cylinder 1 — Low compression from worn rings, cylinder sleeve, valves or head gasket on cylinder 1 reduces contribution.1
  4. Low injection control pressure affecting cylinder 1 contribution — System-wide low ICP from high-pressure oil leaks, sticking IPR valve, low/aerated oil or worn high-pressure oil pump can make cylinder 1 appear weak in the test.4
  5. Incorrect engine oil or aerated oil affecting HEUI operation — Wrong viscosity or aerated oil reduces HEUI control pressure and injector performance, which can trigger a contribution failure.4
  6. Faulty camshaft position sensor signal during test — Erroneous CMP signal can affect timing and contribution evaluation; CMP faults are known no-start/stall issues on this platform.5

How to diagnose

  1. Verify code with a Navistar-compatible scan tool and confirm DTC 461 is present and active; note any accompanying codes.
  2. Inspect cylinder 1 injector electrical connector and harness for corrosion, oil intrusion or damage; check injector coil resistance per service specs.
  3. Perform a cylinder contribution test with the scan tool under load and observe RPM drop for cylinder 1 versus others.
  4. Check injection control pressure actual vs desired at idle and under load; look for low ICP or inability to reach target.
  5. Inspect high-pressure oil system for external leaks, oil condition and level; check IPR valve operation and ICP sensor readings.
  6. If electrical and oil pressure are normal, evaluate mechanical health of cylinder 1 (compression test) to rule out internal engine issues.
  7. Clear codes, road test, and re-check for DTC 461 recurrence; monitor related codes 421-456, 513-525, 333, 241 for injector circuit or ICP issues.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
Internal engine repair (cost depends on teardown findings)Depends on findingsDepends on findingsShop
Wiring or connector repair$10–$1001–4 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 system diagnosis is required, or internal engine mechanical testing is needed, have a qualified diesel technician perform the work. 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

  1. Curated DTC 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) ↩︎