HiAce Van (2KD): Rough idle / vibration
Suspect the supply pump (high-pressure fuel pump) and the injectors first; they are tied in our cases. On the 2.5L 2KD diesel, idle becomes unstable when the pump can't build pressure or the injectors can't spray properly. Next comes a clogged fuel filter. Sometimes replacing only the SCV (the valve that meters fuel into the pump) fixes it.
What to suspect, in order
- How to tell (things you can check yourself)
- Idle vibration plus black or white smoke and loud combustion clatter. The scan tool's per-cylinder correction values show it.
- If you leave it
- Poor combustion makes more soot, and on DPF-equipped vehicles clogs the DPF too.
- Typical repair cost
- Too few cases with a recorded price to give a figure
- Typical model years and mileage
- 129,591–257,591 km (median 247,954 km)
- How to tell (things you can check yourself)
- Revs hunt first thing in the morning or at traffic lights, starting gets harder, the check engine light may come on. Progresses to stalling.
- If you leave it
- Once it can't build fuel pressure the engine stops on the move. Repairs tend to be expensive, so act early.
- Typical repair cost
- Too few cases with a recorded price to give a figure
- Typical model years and mileage
- 79,400–239,400 km (median 157,000 km)。Concentrated on high-mileage vehicles.
- How to tell (things you can check yourself)
- Filter overdue for replacement; symptoms worse after refuelling or on cold mornings. The cheapest thing to check first.
- If you leave it
- A blockage prevents pressure build-up and loads the pump.
- Typical repair cost
- Too few cases with a recorded price to give a figure
- How to tell (things you can check yourself)
- Suspected when fuel pressure faults persist after injectors and pump have been replaced. Hard to tell yourself.
- If you leave it
- Pressure can't be held and stalling repeats.
- Typical repair cost
- Too few cases with a recorded price to give a figure
- How to tell (things you can check yourself)
- Idle vibration plus a choked, sluggish feel at low revs. Typical of an EGR valve stuck with soot.
- If you leave it
- Combustion worsens, black smoke and soot increase, and the intake side clogs.
- Typical repair cost
- Too few cases with a recorded price to give a figure
Confirm with an inspection. Check when the fuel filter was changed, then have a workshop measure fuel pressure.
FAQ
- Will a fuel additive fix it?
- Light deposits may respond, but it does nothing for worn pumps or injectors. If the vibration persists, get it checked.
- How much does the repair cost?
- A fuel filter is cheap; a supply pump or injectors mean serious parts costs. Having it diagnosed first is cheaper in the end.
Sources
- Repair shop blogs (Japan)（3 cases）
- MLIT Vehicle Defect Information Hotline (Japan)（3 cases）
Created by processing the Vehicle Defect Information Hotline data (Ministry of Land, Infrastructure, Transport and Tourism, Japan) (https://renrakuda.mlit.go.jp/renrakuda/opn.html)
No text is quoted from these sources. Only the facts of each case (model, symptom, cause, cost) are aggregated.
Reviewed by Tama Inc. (workshop certified by the Kanto District Transport Bureau) Reviewed on 2026-09-11 Updated 2026-09-11
This page shows what to suspect first, based on aggregated nationwide repair cases and our own experience. Always confirm the cause with an inspection. Repair costs are medians and ranges from the cases; they vary by vehicle condition, region and workshop.
2KD rough idle is SCV and injectors. Fit a new fuel filter first and see — the cheapest step with the fewest misses.