Opel Astra
De-tuned variant of the Z20NET with 120 kW – technically largely identical. The engine is considered reliable from model year 2006. Bypass valve problems and chain wear are shared with the Z20NET.
Turbo entry level
125 kW with turbo character – noticeably livelier than the naturally aspirated engines; the typical turbo grin appears when overtaking.
Engine Weaknesses 4
On early engines (pre-facelift up to approx. 2006), the long front timing chain guide rail can fracture, snapping the bolt. Broken pieces fall into the oil sump. Risk of secondary engine damage from impaired oil circulation.
Symptoms: Rattling on cold start easing as it warms up; engine warning light on more severe damage; in extreme cases sudden engine failure
Identical problem to the Z20NET: the bypass valve membrane tears and boost pressure drops. On the Z20NEL with 120 kW the boost is set lower, but the valve is the same part and equally prone to failure. Cheap to repair.
Symptoms: Intermittent power loss, bypass valve regulation out of target range fault message, sluggish throttle response
The water pump sits behind the turbocharger and auxiliary timing chain cover, as on the Z20NET. A fault requires removal of the turbocharger and secondary chain, considerably increasing the labour involved. Coolant loss is the primary symptom.
Symptoms: Dropping coolant level with no visible external leaks, coolant smell, slight temperature rise in city traffic
At high mileage, valve stem seals harden, allowing engine oil to pass the valve stems into the combustion chamber. Typically first visible as a blue smoke puff when pulling away after a long stationary period.
Symptoms: Blue smoke puff from exhaust immediately after pulling away following a long stationary period, slightly elevated oil consumption with no other cause
Vehicle Weaknesses 10
The M32 6-speed manual gearbox has undersized bearings in the gearbox casing. The bearings cannot cope with the factory tolerances long-term, resulting in whining in 5th/6th gear and gear lever vibration on load changes.
The AC condenser sits low in the front end and is heavily exposed to stone damage. Damaged fins lead to refrigerant loss.
The rear brake discs on the Astra H are prone to heavy surface corrosion, especially on vehicles that see little use. Discs often need replacing due to rust rather than wear.
On the Astra H 1.8 petrol engine the oil cooler gaskets fail, creating an oily, sludgy residue in the coolant expansion tank. If ignored, the cooling circuit becomes contaminated.
The electrohydraulic power steering on the Astra H fails intermittently or permanently. Cause: earth fault at the A-pillar to the CIM control unit, or faulty power steering pump. Steering becomes heavy.
Moisture penetrates through the chrome strip at the tailgate lower edge. The sealing is inadequate, leading to zinc bloom and rust under the paint.
The front axle anti-roll bar drop links wear comparatively quickly on the Astra H. Worn drop links cause dull knocking when cornering or over bumps.
Water enters the Astra H estate's boot through porous tailgate seals or leaking roof rail seam sealant. Moisture damage to the carpet and electronics is possible.
Recall (Opel): A contact fault in the steering column module (CIM) causes the horn to fail on Astra H and Zafira B (2004–2010). Affects hundreds of thousands of vehicles.
In the Astra H, plastic clips and trim around the interior mirror, instrument cluster, and centre console loosen. Creaking and rattling at certain RPM levels or road surfaces.
