1.7 CDTI vs 2.3 dCi (M9T): which engine is more reliable?

According to our risk index, the 2.3 dCi (M9T) carries less risk than the 1.7 CDTI: 32/100 versus 36/100 (both moderate risk). The 1.7 CDTI has 3 documented serious faults, the main one being «Dual-mass flywheel and clutch wear»; the 2.3 dCi (M9T) has 2 documented serious faults, the main one being «Clogged or broken EGR valve damaging the turbo».

Risk index

1.7 CDTI

Moderate risk · 3 serious faults

Risk index

2.3 dCi (M9T)

Moderate risk · 2 serious faults

Lower risk

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 5 October 202614 sources How we work

Is the 1.7 CDTI reliable?

The 1.7 CDTI (Isuzu, 2003-2015) is a simple, widely used diesel, but it has built up accounts of soot-fouled EGR valves and injectors, a clogged diesel particulate filter (DPF) with oil dilution, wear of the dual-mass flywheel and clutch, and of the Hitachi-brand alternator; it also requires the timing belt to be changed every 150,000 km or 6 years to avoid a serious failure.^{[1][2][3][4][5][6][7]}

See the 5 of the 1.7 CDTI faults

Is the 2.3 dCi (M9T) reliable?

The 2.3 dCi M9T is a van diesel with good durability if maintenance is kept up. The weak points cited are the EGR and the turbo, the injectors, and the particulate filter in urban use; the sources are mostly opinion websites.^[8][9]

See the 5 of the 2.3 dCi (M9T) faults

Side-by-side comparison

Comparison of 1.7 CDTI and 2.3 dCi (M9T)
Item	1.7 CDTI	2.3 dCi (M9T)
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,686 cm³	2,300 cm³
Timing	Timing belt (dry)	Chain
Power	100–130 hp	100–180 hp
Production	2003–2015^[1][10][11]	since 2010^[8][9][12]
Reliability
Risk index (what is it?)	36Moderate risk	32Moderate risk
Documented faults	5	5
Of high or critical severity	3	2
Worst severity	Critical severity	High severity
Main faults	High severity: Dual-mass flywheel and clutch wear High severity: Clogged diesel particulate filter (DPF) and oil dilution Critical severity: Timing belt: risk of serious failure if not changed on time	High severity: Clogged or broken EGR valve damaging the turbo Medium severity: Faulty injectors on the 2.3 dCi Medium severity: Diesel particulate filter (DPF) clogged in urban use
Most expensive documented repair	No reliable data	up to €2,300Clogged or broken EGR valve damaging the turboPublished figure^[8][13]
Which versions to buy
BuyRecommended versions	None	2.3 dCi 100-125 hp (M9T)^[9] 2.3 dCi 130-145 hp (M9T)^[9]
With cautionVersions to be cautious about	1.7 CDTI 100-101 hp (Z17DTH, 2003-2007)^[6][7] 1.7 CDTI 110 hp (Z17DTJ/A17DTJ/A17DTC/A17DTE, 2007-2014)^[6][7] 1.7 CDTI 125 hp (Z17DTR/A17DTR, 2006-2013)^[2][3] 1.7 CDTI 130 hp (A17DTS, 2010-2015)^[6][7]	2.3 dCi 150-180 hp (M9T, some twin-turbo)^[9] 2.3 dCi in the Navara D23 (NP300)^[14]
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

1.7 CDTI

See the 7 models with the 1.7 CDTI

2.3 dCi (M9T)

Other comparisons

With the 1.7 CDTI

With the 2.3 dCi (M9T)

Compare other engines

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Sources

Every fact on this page links to its source. If you find an error, let us know.

Circle L engineWikipedia (inglés) · Other source · consulted 27 September 2026
Essai complet Opel Astra (H) : fiabilité et avisFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
Essai complet Opel Zafira 2 : fiabilité et avisFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
Essai complet Opel Meriva : fiabilité et avisFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
Opel Astra H (A04): Probleme & KaufberatungGebrauchtwagenberater.de · Other source · consulted 27 September 2026 · in German
Opel Meriva A: ProblemeGebrauchtwagenberater.de · Other source · consulted 27 September 2026 · in German
Opel Meriva B: ProblemeGebrauchtwagenberater.de · Other source · consulted 27 September 2026 · in German
Renault Master III 2.3 dCi 130: fiabilité, pannes et coûtsCarverif · Other source · consulted 5 October 2026 · in French
Fiabilité Renault Master 2.3 dCiCarverif · Other source · consulted 5 October 2026 · in French
Opel Corsa DWikipedia (alemán) · Other source · consulted 27 September 2026 · in German
Opel MerivaWikipedia (alemán) · Other source · consulted 27 September 2026 · in German
Renault Master (tercera generación)Wikipedia · Other source · consulted 5 October 2026
Fiabilité du Renault Master RT 2.3 dCi: analyse complèteCarverif · Other source · consulted 5 October 2026 · in French
Nissan Navara wymaga zmian systemu oczyszczania spalinAutokatalog.pl · Motoring press · published 23 August 2023 · consulted 5 October 2026 · in another language