ModerateAffected: 2012-201570,000–140,000 miles

Vauxhall Astra Astra J 1.6 CDTi 110bhp — Diesel Injector Seal Leaks

Injector copper sealing washers on the Astra J 1.6 CDTi harden and allow combustion gases to bypass the injector seat. This causes carbonisation around the injector tops and eventually rough running.

Severity

Moderate

DIY Difficulty

Hard

Est. Cost

£150–£300

OBD Codes

None

Component Diagram

Injectors

Typical layout and location for the Injectors assembly.

Reference Illustration

Symptoms

Diesel or combustion smell from engine bay
Black carbon deposits around injector tops
Rough idle at low temperature
Occasional misfire codes
Slight diesel weep visible

Root Cause

The copper crush washers that seal each injector against the cylinder head compress and deform permanently over many heat cycles. Once the seal loses clamping force, combustion gases and fuel bypass the seat.

How To Fix

Remove injectors and fit new copper crush washers (£2-5 each) and O-rings
Clean injector bore with correct cleaning tool before refitting
Re-torque to spec — over-tightening damages the head
Full job: £150-300 at indie

Estimated Repair Costs

Repair Option	Est. Cost (GBP)
DIY (parts only)	£60–£120
Independent Garage	£150–£300
Main Dealership	£240–£480

Other Faults on This Variant

Timing Chain Rattle and Tensioner Failure

Critical

2012-201560,000–120,000 miles£800–£1500

The 1.6 CDTi A16DTH/DTJ engine is notorious for timing chain noise and failure, often from as low as 60,000 miles. This is the most serious known fault on the Astra J diesel.

Clutch Pedal Sticking Down

Severe

2009-201550,000–100,000 miles£150–£700

The clutch pedal fails to return to the top of its travel, often getting stuck halfway or hitting the floor completely.

DPF Blockage and Regeneration System Failure

Severe

2012-201540,000–90,000 miles£200–£1000

DPF blockage is extremely common on the Astra J 1.6 CDTi. The engine's tendency to get stuck in failed regen cycles results in diesel contaminating the engine oil — a serious secondary issue.

Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.