Known faults for the Audi A4 (B9).

Engine / equipment

Air conditioning with clutchless compressor and N280 regulating valve (combustion VW, Audi, Seat, Cupra and Skoda from 2006)

Period mentioned

2006–2026

Symptoms

The air does not cool or cools intermittently (for example only at motorway speed), and sometimes the compressor rattles with the A/C on. Codes 01232 (N280 valve), P2612 or 00898.

Possible cause described

The compressor regulates its output with the N280 solenoid valve, its most common failure point. Audi issued technical bulletins over a manufacturing fault in this valve on Sanden compressors. Its connector can also become brittle and corrode (especially without the engine undertray), or the wiring fails.

Check for the garage

Read the codes and N280 control current with VCDS or ODIS, measure its resistance (about 10 ohms) and check the connector and wiring before replacing parts. If the valve or compressor is replaced, the whole circuit must be flushed.

Cost cited in the source

N280 valve: a cheap part (about 30 dollars) where sold separately; new compressor with circuit flush: considerably moreA rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

EA211 1.0, 1.2 and 1.4 TSI/TFSI petrol (Golf VII, Polo, Octavia III, Leon 5F, A3 8V, Ibiza, Fabia III and other MQB cars)

Period mentioned

2012–2020

Symptoms

Coolant level drops slowly with no visible puddle, dried white or pink residue behind the engine, a sweet smell and a low-level warning. If loss continues, it can overheat.

Possible cause described

The water pump is built into a plastic housing with the thermostats, which warps and cracks with heat cycles, and its seals degrade. A trade magazine also notes that oil from a nearby leak (for example the crankcase ventilation) speeds up failure of the housing and the pump belt.

Check for the garage

With the engine cold, monitor the level for several days and look for dried residue around the housing and the coolant pipe under the air box. At a garage: pressure test and check for nearby oil leaks. Replacing pump and housing as one assembly is recommended; do not use stop-leak products. Never open the system hot.

Cost cited in the source

A reliability guide quotes €500–1,000 for the 1.4 TSI and €300–600 for the 1.2 TSI.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

1.8 and 2.0 TSI/TFSI EA888 gen 3 (Golf VII GTI/R, A3/S3 8V, TT 8S, A4 B9, Octavia III, Leon III, Passat B8, Tiguan II, Superb III…)

Period mentioned

2012–2020

Symptoms

Slow coolant loss, sweet smell, low-coolant warning and coolant residue under the intake manifold. Overheating is rare unless the level drops a lot.

Possible cause described

The water pump and thermostat form a single plastic module next to the exhaust that cracks with heat cycling. It often fails before 100,000 km and Volkswagen recognises it as a design fault.

Check for the garage

Look for coolant residue where the module meets the block and between pump and thermostat, check the level and pressure-test the system.

Cost cited in the source

Complete pump and thermostat module with coolant: approx. €470–740 at a specialist (converted from Canadian dollars)A rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: up to 100,000 km. This is not a maintenance interval and does not predict a failure.

Sources from the original database

Engine / equipment

1.6 and 2.0 TDI (EA189 and EA288)

Period mentioned

Approx. 2010–2020

Symptoms

Coolant level drops with no visible leak, white smoke with a sweet smell, rising temperature or engine light. In severe cases the engine hydrolocks.

Possible cause described

The internal tubes of the EGR cooler crack and coolant enters the intake. It worsened after the post-Dieselgate software update, which increased EGR use.

Check for the garage

Cooling system pressure test and check for coolant in the intake or manifold.

Cost cited in the source

€400–1,300A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

2.7 and 3.0 TDI V6 (EA896 and EA897): Audi A4, A5, A6, A7, A8, Q5, Q7; VW Touareg, Phaeton and Amarok; Porsche Cayenne, Macan and Panamera

Period mentioned

2004–2018

Symptoms

Chain rattle for the first seconds after a cold start; power loss or limp mode from the intake flaps; coolant or oil loss in the engine V; EGR faults with rough idle.

Possible cause described

The timing chains sit at the rear of the engine, against the bulkhead, and their tensioners lose pressure. The intake flaps use plastic linkage rods that wear. The coolant valve, oil cooler gasket and EGR are packed into the engine V and leak with age.

Check for the garage

Listen to a cold start (a rattle lasting more than 2–3 seconds is a bad sign), check flap operation with a diagnostic tool, look for leaks in the engine V and check the oil change history.

Cost cited in the source

Tensioners and chains: approx. €2,000–4,500; EGR with cooler: €1,000–1,500; oil cooler gasket: €300–600A rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: 100,000–150,000 km. This is not a maintenance interval and does not predict a failure.

Sources from the original database