Is the Saab 1.9 TiD the same engine as the Vauxhall 1.9 CDTi?

Yes. The Saab 9-3 1.9 TiD uses the identical Z19DTH engine with the same Bosch injectors.

How much does Z19DTH injector replacement cost?

A set of four costs £350-£600. Labour is 2-3 hours.

Do Z19DTH injectors need coding?

Yes. IMA coding via Vauxhall Tech2, MDI, or compatible diagnostic tool is required.

How much does it cost to replace injectors?

Replacement typically costs £150–£350 per injector depending on brand and engine. A full set of four with professional fitting usually costs £600–£1,200.

Can I drive with a faulty injector?

Driving with a faulty injector can cause engine damage, increased fuel consumption, DPF contamination, and oil dilution. We recommend diagnosis and replacement as soon as possible.

Do new injectors need coding?

Some vehicles require injector coding after replacement using manufacturer-specific diagnostic tools. Many Bosch solenoid units are plug and play. Check your engine guide for specific requirements.

Why is my diesel injector knocking?

Diesel injector knocking is typically caused by worn nozzle tips that alter the fuel spray pattern, leading to harsher combustion. Carbon buildup, incorrect injection timing, and high fuel pressure can also contribute. A professional leak-off test can confirm whether injectors are the cause.

Can a bad injector cause white smoke?

Yes. A faulty injector that dribbles fuel instead of atomising it causes incomplete combustion, producing white or grey smoke. This is especially noticeable on cold starts and typically clears as the engine warms up.

How long do diesel injectors last?

Most diesel injectors last between 80,000 and 150,000 miles depending on fuel quality, driving conditions, and maintenance. Regular fuel filter changes and using quality diesel can extend their lifespan.

Will injector cleaner fix misfire?

Injector cleaner may help with minor carbon deposits, but it cannot fix worn nozzles, failed solenoids, or internal seal leaks. If misfire persists after using cleaner, professional testing and likely replacement is needed.

Vauxhall Z19DTH 1.9 CDTi 150hp Injector Problems: Symptoms & Repair (UK)

Updated for 2026 diagnostics & repair guidance

Fiat-sourced engine. Same injectors as Alfa Romeo and Saab 1.9 diesels.

The Z19DTH is a Fiat-sourced 1.9 CDTi engine used across Vauxhall's range. Found in the Vectra C, Astra H, Signum, and Zafira B, it uses Bosch solenoid injectors. The 150hp version is the most common in the UK and injector failures are well-documented.

OEM tested & calibrated12-month warrantyFree UK deliveryNo coding required (most models)

OEM Tested
12-Month Warranty
Free UK Delivery

Registration Lookup Find Matching Z19DTH Injector

Drivers also ask

Quick Diagnosis

If your Z19DTH engine shows:

rough idle
hard starting
white or black smoke
knocking or ticking noise
reduced fuel economy

A faulty injector may be the cause. Continue below to confirm symptoms and solutions.

Can You Drive With This Problem?

Driving short distances may be possible, but continued use can cause:

piston damage
turbo contamination
fuel dilution of engine oil
catalytic converter damage

Prolonged driving may lead to major engine failure.

Typical Repair Costs (UK)

Average costs for injector-related repairs:

£180 - £350

Per Injector

£700 - £1,200

Full Set (4)

£120 - £300

Labour

Early replacement prevents costly engine damage.

Common Injector Failure Symptoms

Owners frequently report:

Rough idle and vibration

Injector imbalance causes the engine to run unevenly at idle.

Black smoke under acceleration

Over-fuelling from worn nozzles.

Loss of power

The ECU limits output when injector deviation is detected.

Diesel smell from engine bay

External leaks at injector seals.

Full symptom guide White smoke guide

Fault Codes Linked to Injector Issues

Common diagnostic codes include:

P0201-P0204Injector circuit malfunction

P0087Fuel rail pressure too low

Misfire diagnosis guide

How to Diagnose Z19DTH Injector Faults

Follow this step-by-step testing approach to identify the faulty injector:

1
Read fault codes
Connect an OBD-II scanner and note any injector-related codes (P0201–P0204, P2146, P2149). This identifies which cylinder is affected.
2
Perform a leak-off test
Disconnect the fuel return pipes and route into measuring containers. Run the engine at idle for 60 seconds. Compare volumes per cylinder against manufacturer spec.
3
Listen for injector tick
Use a mechanic's stethoscope on each injector body. A dead or irregular tick indicates a stuck or failing solenoid.
4
Check fuel rail pressure
Monitor live fuel rail pressure data via diagnostic tool. Low pressure can mimic injector symptoms and may indicate a fuel pump issue instead.
5
Inspect for external leaks
Check around injector seals for signs of fuel or combustion gas leakage. Black carbon deposits indicate a blown seal.
6
Cylinder balance test
Use diagnostic software to run a cylinder contribution test. This electronically disables each injector in turn to measure its effect on engine speed.

Full leak-off test guide Injector coding guide

Why Z19DTH Injectors Fail

Common causes include:

fuel contamination
high-pressure wear cycles
carbon buildup
poor fuel quality
internal valve wear

Professional remanufacturing restores spray pattern and pressure accuracy.

When Replacement Is Required

Injector replacement is recommended if:

leak-off test fails
misfire persists after coding
excessive return flow detected
spray pattern fails testing
vehicle enters limp mode

Z19DTH Repair Advice

The Z19DTH uses Bosch solenoid injectors. IMA coding is required via Tech2 or compatible tool. The same injectors are used in Saab 9-3 and Alfa Romeo 159 versions.

Remanufactured (Recommended)

OEM-spec rebuild with new nozzles, seals, and solenoids. Full flow testing. 12-month warranty. 40–60% less than new.

Brand New OEM

Factory-fresh from Bosch, Delphi, or Siemens. Highest cost but zero previous wear. Best for low-mileage vehicles.

Vehicles Using the Z19DTH Engine

This engine is commonly found in:

Vauxhall Vectra C

1.9 CDTi 120/150 · 2004-2008

Vauxhall Astra H

1.9 CDTi 120/150 · 2004-2010

Vauxhall Zafira B

1.9 CDTi 120/150 · 2005-2011

Saab 9-3

1.9 TiD 150 · 2004-2012

Alfa Romeo 159

1.9 JTDm 150 · 2005-2011

Professional Installation Tip

Always:

replace copper sealing washers
torque injectors to manufacturer specification
clean injector seats before installation
code injectors after installation (if required)

Leak-off test guide Injector coding guide

Compatible Injector Part Numbers for Z19DTH

The following injector part numbers are commonly associated with Z19DTH engines:

Bosch

0445110276

Bosch injector for Z19DTH 150hp

£70.00View details

Vauxhall

55200259

Vauxhall OE reference

£70.00View details

Also commonly fitted:

0445110159Bosch

Z19DTH Injectors — Shop Now

In-stock injectors listed first for fastest delivery:

VAUXHALL ASTRA ( ASTRA ARCTIC CDTI A3300) 1.9L Diesel Injector

£100.00

Made to order12 months

VAUXHALL ASTRA ( ASTRA ACTIVE CDTI T98) 1.7L Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( Astra Active CDTi P10) 1.7L 2012-2013 Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( ASTRA ACTIVE CDTI T98) 1.7L 2003-2005 Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( ASTRA ACTIVE LTD EDITION CDTI A3400) 1.7L Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( ASTRA BELMONT LD DIESEL ) 1.7L Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( Astra Business Edition Nav TD B16) 1.5L 2021- Diesel Injector

£120.00

Made to order12 months

VAUXHALL ASTRA ( Astra Business Edition Nav TD B16) 1.5L 2019-2021 Diesel Injector

£120.00

Made to order12 months

View all Z19DTH injectors

These injectors are commonly used with the Z19DTH engine. Confirm compatibility using your engine code or registration lookup before ordering. Our team can verify the correct part for your specific vehicle.

Helpful Guides

Reconditioned injectors guide

How remanufactured injectors are tested & warranted

Injector warranty guide

What's covered & how to claim

UK delivery & fitment help

Free next-day delivery & part-number checks

Find Your Exact Z19DTH Injector

Three quick ways to confirm the right part:

Registration Lookup

Enter your reg to find the exact part

Engine Code Search

Search using Z19DTH

Same-day dispatch before 2pm12-month warranty includedOEM tested & calibrated

Not sure which injector? Call us on 020 3355 6581.

Frequently Asked Questions

Injector Symptoms

Spot the warning signs of a failing diesel injector

Injector Fault Codes

P0201–P0204 injector circuit codes explained

Smoke Diagnosis

White & blue smoke causes and fixes

Injector Testing

Leak-off & bench testing methods

Replacement Cost

UK parts + labour cost breakdown

Misfire Diagnosis

Why injectors cause rough running & misfires

A20DTH Injector Problems

Vauxhall/Opel

OM651 Injector Problems

Mercedes-Benz

N47 Injector Problems

BMW

B47 Injector Problems

BMW

Transit 2.2 TDCi Injector Problems

Ford

DW10C Injector Problems

PSA Group (Peugeot/Citroen)

Related commercial guides

Remanufactured Injectors

OEM-rebuilt, every wear part replaced, 12-month warranty

Reconditioned Injectors

Bench-tested, calibrated, UK same-day dispatch

Refurbished Injectors

Cleaned, nozzle-replaced, flow-tested — cheaper than reman

Used Diesel Injectors

Read this before you buy — risks, checks, real cost

Buyer-intent comparisons

Remanufactured vs New

Same lifespan, 40–60% cheaper — when reman wins, when new wins

Replacement Cost UK 2026

Parts + labour + coding — per-engine UK pricing tables

Best Place to Buy UK

7 quality signals, warranty wording, core-return checks

Vauxhall Z19DTH 1.9 CDTi 150hp Injector Problems: Symptoms & Repair (UK)

Drivers also ask

Quick Diagnosis

Can You Drive With This Problem?

Typical Repair Costs (UK)

Common Injector Failure Symptoms

Rough idle and vibration

Black smoke under acceleration

Loss of power

Diesel smell from engine bay

Fault Codes Linked to Injector Issues

How to Diagnose Z19DTH Injector Faults

Read fault codes

Perform a leak-off test

Listen for injector tick

Check fuel rail pressure

Inspect for external leaks

Cylinder balance test

Why Z19DTH Injectors Fail

When Replacement Is Required

Z19DTH Repair Advice

Remanufactured (Recommended)

Brand New OEM

Vehicles Using the Z19DTH Engine

Professional Installation Tip

Compatible Injector Part Numbers for Z19DTH

Z19DTH Injectors — Shop Now

Helpful Guides

Find Your Exact Z19DTH Injector

Frequently Asked Questions

Related Guides

Related Engine Problems

Other Engine Guides

Related commercial guides

Buyer-intent comparisons