Citroën DS4

High-output variant with interference engine. Under higher engine load a belt snap immediately causes valve contact. Premature wear possible from 60,000–80,000 km. Workshop costs after engine damage: €3,000–6,000.

Symptoms: Sudden engine stall, no restart, metallic noise on snap.

The more heavily loaded turbocharger in the 163 hp version tends to earlier bearing wear with insufficient oil change intervals. First weaknesses often from 60,000–80,000 km. Check turbo oil feed lines for sludge.

Symptoms: Power loss, whistling/rattling noises from the turbo, blue exhaust, warning light.

Eolys additive-based FAP system only regenerates adequately on motorway driving. Failed regenerations translate into oil dilution. Frequent short trips lead to premature filter replacement.

Symptoms: FAP warning light, power reduction, significantly increased fuel consumption, diesel smell in oil.

The DW10-163 oil pump shows wear at higher mileages. Oil pressure drops and is no longer sufficient for adequate lubrication of the turbo and bearings. Mechanical noises announce oil pressure loss.

Symptoms: Oil pressure warning at operating temperature at idle, knocking noises from the engine, oil pressure warning light occasionally flashing. Oil pressure measurement shows below 1.5 bar at idle.

On the high-output 163 hp version, injectors can coke up, especially if the engine is frequently run at full load and then shut down immediately. Poor fuel quality accelerates deposits.

Symptoms: Rough idle, hesitation at part load, increased fuel consumption, soot smell.

The turbocharger wastegate valve cokes up from soot deposits and sticks in one position. With the wastegate open, no boost pressure builds up. The vacuum hose to the actuator is often porous. Solenoid valve overheats.

Symptoms: Sudden power loss especially under load, turbo fails to build boost, engine feels like a naturally aspirated unit. Solenoid valve hot and buzzing at 88% duty cycle.

The electric power steering in the DS4 I can fail — the steering servo motor gives up, making the steering extremely heavy. Causes are typically ECU faults or defective connectors at the column motor.

The EGS6 automated manual gearbox (later renamed ETG6) in the DS4 I is prone to premature clutch wear. The dual-clutch slips and causes jerky shifts, especially with torquey diesel engines. Repairs are expensive.

The central BSI control unit in the DS4 I is prone to software faults that simultaneously trigger warning lights for ABS, ESP, ASR and the parking brake. The cause is often moisture in connectors or a weak 12V battery.

Corrosion at the ABS sensor wheel bearing seats causes the sensors to seize and become impossible to remove. The underfloor can also rust broadly on neglected vehicles.

Brake discs on the DS4 I wear above average, especially in urban use. Surface rust after extended standstill causes loud squealing on the first braking application. Front discs are more severely affected.