Vauxhall Signum problems, reliability and years to avoid
If you are considering buying a used Vauxhall Signum, these are the common problems worth knowing about first. Our garage database tracks 5 known faults for this model, 5 of them rated high severity. Every one below is a repair bill a seller has good reason not to mention.
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Is the Vauxhall Signum reliable?
The Vauxhall Signum has 5 known faults in our database, 5 of them rated high severity. The most serious are engine (failed timing belts on the 1.9 CDTi, often due to a seized water pump) and engine (failed inlet manifold swirl flaps on the 1.9 CDTi engine). None of them makes the car a bad buy on its own; the risk is a seller who knows and says nothing.
That is a count of the faults we hold, not a reliability score. Popular cars get written about more, and a newer generation has had less time to show its faults.
Which Vauxhall Signum years should you avoid?
No year is a write-off on its own. What matters is which serious faults a given year and engine can have, and whether the car in front of you has had them fixed.
Years and engines with a serious known fault
2004 to 2010, 1.9 CDTi (Z19DT 120hp and Z19DTH 150hp), in the Astra H, Zafira B, Vectra C and Signum: failed timing belts on the 1.9 CDTi, often due to a seized water pump
2004 to 2010, 1.9 CDTi (Z19DTH 150hp), in the Astra H, Zafira B, Vectra C and Signum: failed inlet manifold swirl flaps on the 1.9 CDTi engine
2004 to 2010, Torque converter automatics, especially the diesels (Astra H, Zafira B, Vectra C and Signum): joints of the heat exchanger in the radiator header tank can fail
2003 to 2008, 2.2 Direct petrol (Z22YH, 155PS, direct injection); not the port-injected 2.2 16v Z22SE these cars had before it: the Siemens high-pressure fuel pump and the fuel pressure sensor on the 2.2
2002 to 2008, 2.2 16v petrol: Z22SE (to about 2004) and 2.2 Direct Z22YH (from 2003): the timing chain on the 2.2 petrol stretches
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
Generation 1 of 15 known faults · 1 owner report · 2 good notes
Failed inlet manifold swirl flaps on the 1.9 CDTi engine. The flaps can break off and be ingested by the engine, causing severe damage. Sooting up and seizing of the secondary butterflies is also common, leading to hesitation and power loss.
Rough guide
£800-2000
Typical symptoms
Engine smoking
Sudden loss of power or limp mode
Hesitation while cruising
Engine warning light
Affected vehicles
Engines:
1.9 CDTi (Z19DTH 150hp), in the Astra H, Zafira B, Vectra C and Signum
Typical mileage:
60000-100000 miles
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Failed timing belts on the 1.9 CDTi, often due to a seized water pump which is driven by the belt. The tension of a new belt can rapidly wear the water pump bearing, leading to seizure and belt failure, potentially wrecking the engine. Replacement of belt, tensioner, pulleys, and water pump is crucial every 40,000 miles.
Rough guide
£1000-2000
Typical symptoms
Sudden loss of engine power
Engine stops running
Metallic noises from engine bay
Coolant leaks
Affected vehicles
Engines:
1.9 CDTi (Z19DT 120hp and Z19DTH 150hp), in the Astra H, Zafira B, Vectra C and Signum
Typical mileage:
40000-60000 miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
Transmission/ClutchHigh severity📝 Editorial
Joints of the heat exchanger in the radiator header tank can fail, allowing coolant to mix with the automatic transmission fluid, which can wreck the transmission. This is a very expensive repair.
Rough guide
£4000-5000
Typical symptoms
Automatic transmission slipping or shifting poorly
Contaminated transmission fluid (milky or discoloured)
Overheating transmission
Coolant loss without obvious external leak
Affected vehicles
Engines:
Torque converter automatics, especially the diesels (Astra H, Zafira B, Vectra C and Signum)
Typical mileage:
60000-100000 miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
Fuel SystemHigh severity📝 Editorial
The Siemens high-pressure fuel pump and the fuel pressure sensor on the 2.2 Direct petrol fail, the same fault the Zafira B 2.2 has. Failures peaked in autumn 2008 with a shortage of replacement pumps; the pump was about 315 pounds and a typical repair about 545 pounds. The engine's fault code doesn't say whether the pump (leaking seal) or the pressure regulator (sticking valve) is to blame.
Rough guide
£500-600
Typical symptoms
Engine cutting out or failing to start
Intermittent loss of power
Engine management light on
Rough idling
Affected vehicles
Engines:
2.2 Direct petrol (Z22YH, 155PS, direct injection); not the port-injected 2.2 16v Z22SE these cars had before it
Typical mileage:
Unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
Engine/EmissionsHigh severity📝 Editorial
The timing chain on the 2.2 petrol stretches and can jump teeth or snap when the chain tensioner blocks or its oil feed clogs with dirty oil. Early signs are a rattle from the timing chain, misfiring and erratic running; if the chain jumps, the engine can be wrecked. A revised tensioner went into production for model year 2009, and parts makers advise fitting a new chain with it. Regular oil changes with the right oil are the main defence.
Rough guide
£Unknown
Typical symptoms
Rattle from the timing chain, especially on a cold start
Engine management light
Misfire or erratic running
Engine failure if the chain jumps
Affected vehicles
Engines:
2.2 16v petrol: Z22SE (to about 2004) and 2.2 Direct Z22YH (from 2003)
Typical mileage:
Unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
What owners report on the Signum
1 single report, unconfirmed
One owner each, in their own words rewritten as a line, and not counted in our risk scoring. A fault joins the list above once a second report or an editorial source backs it.
Interior · December 2019A Vauxhall Signum experienced a failed climate control module, which was repaired for a cost of around 400 plus VAT.
What owners like about the Signum
2 notes
The Signum offers generous rear seat legroom and enhanced ride comfort for passengers due to its design.
The Vauxhall Signum achieved a four-star rating in NCAP crash safety tests, indicating good occupant protection.
Sellers rarely admit these faults outright
We track 15 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Vauxhall Signum advert and we check it in seconds.
Repair costs are typical UK ranges, not quotes. Actual cost depends on condition and garage.Data last verified: October 2026
Vauxhall Signum buying questions
What are the most common Vauxhall Signum problems?
Three stand out. Engine: failed timing belts on the 1.9 CDTi, often due to a seized water pump which is driven by the belt (typically 40000 to 60000 miles). Engine: failed inlet manifold swirl flaps on the 1.9 CDTi engine (typically 60000 to 100000 miles). Gearbox: joints of the heat exchanger in the radiator header tank can fail (typically 60000 to 100000 miles). The full list above is grouped by generation, with typical mileage and a rough repair cost for each.
Which Vauxhall Signum years should I avoid?
No Vauxhall Signum year is a write-off, but the Signum (2003 to 2008) carries the most serious faults: engine, gearbox and fuel system. Year matters less than whether the specific car has had the known fixes, so check the history for them.
What should I check when viewing a used Vauxhall Signum?
Ask the seller about the engine and gearbox faults on this page and whether they have been fixed, with invoices. On the test drive watch for sudden loss of engine power, engine smoking and automatic transmission slipping or shifting poorly. Read the MOT history for repeat advisories, then paste the advert into the free check, which reads it against all 5 known faults before you travel. Check a Vauxhall Signum advert →
What is the real MPG of a Vauxhall Signum?
Owners report 38.4 mpg on average across the Vauxhall Signum engines with data, about 93% of the official combined figure. The gap between official and real-world economy varies a lot by engine, so the Real MPG page lists every engine and generation separately, from 105 owner submissions. Vauxhall Signum Real MPG by engine →
If you used to check the Honest John “Good & Bad” section before the site closed in 2026, this page is where that information now lives. We rebuilt the Vauxhall Signum owner-report history from the archived Honest John dataset, added our own research, specialist and owner-club sources and DVSA recall data, and we keep it free. Each fault above is badged with its source. The same data feeds our free advert check, which reads a listing against every known fault for the exact engine and year.
Knowing what a Vauxhall Signum goes wrong with is half of it. The rest is reading the advert and checking the car's history before you hand any money over.