This is the engine that made the VW-Audi oil sludge affair famous.
Applies to the engine AUQ.
1999–2004. The fault list covers this generation and the engines in it. If the listing gives the exact version, pick it below.

Rudolf Stricker / Attribution
What to watch for
The list covers the generation, the engines and the transmissions. Once you pick the version, only the faults that apply to it stay.
This is the engine that made the VW-Audi oil sludge affair famous.
Applies to the engine AUQ.
Stress cracks of manufacturing origin can form on the vacuum hose leading to the brake servo, around the connections.
It can affect every car in this generation.
The PD (pump injector) unit is held in the cylinder head by a single side bolt.
Applies to the engine ARL, ASZ.
The internal springs of the flywheel tire, and the two discs knock against each other.
Applies to the engine ALH, AGR, AHF and 3 more.
The PD injectors (on the 1.4, 1.9 and 2.0 TDI alike) are driven by the camshaft itself, against more than 2,000 bar.
Applies to the engine ARL, ASZ.
The vanes of the variable geometry turbo are glued together by soot and oil arriving through the EGR.
Applies to the engine ALH, AHF, ASV and 2 more.
The G62 sensor tells the engine control unit how hot the coolant is.
Applies to the engine AEH, AGN, AGZ and 16 more.
From the late nineties to around 2006, petrol engines used a secondary air pump to blow fresh air into the exhaust on a cold start, so the catalytic converter reaches operating temperature faster.
Applies to the engine AEH, AGN, AGZ and 10 more.
2 more faults belong to this generation. On the version page, only the ones that apply stay.
Engines and transmissions in this generation
A fault is often tied to the engine, not to the whole generation. You find the engine code in the registration document.
II · 1999–2004
The fault list opens on the version page.
43 versions
1.6 l · 1595 cm³
AEH · AKL
1.6 Signo
1999–2004 · Signo
1.6 l · 1595 cm³
APF · AEH · MQ150
1.6 Signo
1999–2004 · Signo
1.6 l · 1595 cm³
AEH · AKL · MQ150
1.6 Signum
1999–2004 · Signum
1.6 l · 1595 cm³
AEH · AKL
1.6 Signum
1999–2004 · Signum
1.6 l · 1595 cm³
AEH · AKL · MQ150
1.6 Sport
1999–2004 · Sport
1.6 l · 1595 cm³
AEH · AKL · MQ150
1.6 Stella
1999–2004 · Stella
1.6 l · 1595 cm³
AEH · AKL
1.6 Stella
1999–2004 · Stella
1.6 l · 1597 cm³
BCB · AUS · MQ150
1.6 16V Executive
1999–2004 · Executive
1.6 l · 1597 cm³
AUS · AZD · MQ150
1.6 16V Signo
1999–2004 · Signo
1.6 l · 1597 cm³
AUS · AZD · MQ150
1.6 16V Spirit
1999–2004 · Spirit
1.6 l · 1597 cm³
AUS · AZD · MQ150
1.6 16V Sport
1999–2004 · Sport
1.6 l · 1597 cm³
AUS · AZD · MQ150
1.6 16V Stella
1999–2004 · Stella
1.8 l · 1781 cm³
AGN · APG
1.8 20V Executive
1999–2004 · 20V Executive
1.8 l · 1781 cm³
AGN · APG
1.8 20V Executive
1999–2004 · 20V Executive
1.8 l · 1781 cm³
AGN · APG
1.8 20V Signo
1999–2004 · 20V Signo
1.8 l · 1781 cm³
AGN · APG
1.8 20V Signo
1999–2004 · 20V Signo
1.8 l · 1781 cm³
AGN · APG
1.8 20V Signum
1999–2004 · 20V Signum
1.8 l · 1781 cm³
AGN · APG
1.8 20V Signum
1999–2004 · 20V Signum
1.8 l · 1781 cm³
AGN · APG
1.8 20V Sport
1999–2004 · 20V Sport
1.8 l · 1781 cm³
AGN · APG
1.8 20V Stella
1999–2004 · 20V Stella
1.8 l · 1781 cm³
AGN · APG
1.8 20V Stella
1999–2004 · 20V Stella
1.8 l · 1781 cm³
AUQ · MQ350
1.8 20VT Executive
1999–2004 · 20VT Executive
1.8 l · 1781 cm³
AUQ · MQ350
1.8 20VT Sport
1999–2004 · 20VT Sport
1.9 l · 1896 cm³
AGR · ALH
1.9 TDi 90hp Signo
1999–2004 · Signo
1.9 l · 1896 cm³
AGR · ALH
1.9 TDi 90hp Signum
1999–2004 · Signum
1.9 l · 1896 cm³
AGR · ALH
1.9 TDi 90hp Stella
1999–2004 · Stella
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Executive
1999–2004 · Executive
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Signo
1999–2004 · Signo
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Signum
1999–2004 · Signum
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Spirit
1999–2004 · Spirit
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Sport
1999–2004 · Sport
1.9 l · 1896 cm³
AHF · ASV
1.9 TDi 110hp Stella
1999–2004 · Stella
1.9 l · 1896 cm³
ASZ · MQ350
1.9 TDi 130hp Executive
1999–2004 · Executive
1.9 l · 1896 cm³
ASZ · MQ350
1.9 TDi 130hp Spirit
1999–2004 · Spirit
1.9 l · 1896 cm³
ASZ · MQ350
1.9 TDi 130hp Sport
1999–2004 · Sport
1.9 l · 1896 cm³
ARL · MQ350
1.9 TDi 150hp Executive
1999–2004 · Executive
1.9 l · 1896 cm³
ARL · MQ350
1.9 TDi 150hp Signo
1999–2004 · Signo
1.9 l · 1896 cm³
ARL · MQ350
1.9 TDi 150hp Sport
1999–2004 · Sport
2.3 l · 2324 cm³
AGZ
2.3 V5
1999–2004
2.3 l · 2324 cm³
AGZ
2.3 V5 Executive
1999–2004 · Executive
2.3 l · 2324 cm³
AQN
2.3 V5 Executive
1999–2004 · Executive
2.3 l · 2324 cm³
AQN
2.3 V5 Signo
1999–2004 · Signo
2.3 l · 2324 cm³
AQN
2.3 V5 Sport
1999–2004 · Sport
Neighbouring generations
II (1M). If the listing is from the changeover year, look at the neighbour too.
Common questions
1999–2004. The changeover year can fall in two generations. If the listing is from that year, look at the neighbour too.
No. It depends on the engine and the transmission too.
The fault list is.
We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.