
EUI injector specialist
EUI injector specialists: precision testing & calibration in Auckland
Restore engine performance with professional Electronic Unit Injector diagnostics, testing, rebuilds and calibration. Simms Diesel services trucks, heavy equipment, marine and industrial engines with fast turnaround and expert workmanship.


Why choose Simms for eui injector repair

Established diesel experts
Trusted diesel injection specialists serving Auckland and Northland for decades.

Advanced EUI calibration & testing
Specialist bench testing and precision calibration equipment ensures every injector is rebuilt and set to exact manufacturer specifications.

Fleet & commercial focused
We understand downtime costs money. Our structured injector repair process keeps your trucks, plant and machinery running reliably.

Quality parts & verified performance
We use quality components and verify every EUI injector through comprehensive testing before it leaves our workshop.
Losing power? Excess smoke or rough idle?
Electronic Unit Injector (EUI) faults can cause hard starting, power loss and inconsistent performance under load. Because EUI systems control fuel delivery electronically and mechanically, accurate bench testing is essential before replacing parts.
If you’re experiencing any of the following, your injectors may need professional inspection:
Common signs your EUI injectors may require testing:
- Hard start / no start (even with good fuel supply)
- Loss of power or poor throttle response
- Excess black or white smoke under load
- Rough idle, misfiring or surging
- Increased fuel consumption
- Fault codes relating to injector performance

Our EUI injector service process
We follow a structured EUI testing and rebuild workflow to ensure accurate diagnosis, reliable repairs and consistent performance — without unnecessary part replacement.
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Inspect & bench test
We perform electronic and mechanical testing to confirm injector faults before any repair work begins. Accurate diagnosis prevents unnecessary replacement costs.
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Strip, rebuild & component replacement
Injectors are carefully dismantled, internal components inspected, and worn parts replaced using quality components matched to manufacturer specifications.
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Precision calibration & verification
Each EUI injector is calibrated and validated on specialised test equipment to ensure correct fuel delivery, timing and performance before leaving our workshop.

Request an EUI injector test or repair
- Typical response time: same business day
- NO-OBLIGATION assessment
- Experienced diesel technicians
- Auckland workshop
Tell us your engine model, EUI injector type and symptoms — we’ll recommend the most cost-effective testing, repair or replacement solution based on proper diagnostics.
Frequently asked questions
Clear answers to common questions about EUI injector testing, rebuilds, exchange options and workshop turnaround.
09 579 1159How long does EUI injector repair take?
Turnaround time depends on injector type and parts availability. In most cases, testing and rebuild work is completed within a few business days. We provide a clear timeframe once bench testing confirms the fault.
Can I courier my injectors to you?
Yes. We accept injectors from workshops and fleet operators across New Zealand. Secure packaging is important to prevent damage in transit — contact us for shipping guidance.
What brands of EUI injectors do you service?
We service a wide range of diesel injection brands including Bosch, Cummins, CAT, Detroit, Volvo, Scania, Perkins, Delphi, Denso, Stanadyne and more. If you’re unsure, contact us with your engine details.
Do you test injectors before repairing them?
Yes. Every EUI injector is electronically and mechanically bench tested before any repair work begins. Accurate diagnosis ensures only necessary components are replaced and prevents unnecessary costs.
Do you offer exchange injector options?
Where available, we can supply remanufactured or exchange EUI injectors to minimise downtime. Availability depends on engine platform and stock levels.
What are common signs of EUI injector failure?
Common symptoms include:
- Hard starting
- Loss of power
- Excess smoke under load
- Rough idle or misfiring
- Increased fuel consumption
- Fault codes related to injector performance
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