Citroën C4 Aircross

The 4N13 in the C4 Aircross suffers from DPF clogging under predominantly short-trip use. Forced regeneration cycles increase fuel entry into the engine oil.

Symptoms: DPF warning light, power loss, rising oil level, fuel smell in oil.

With extended oil change intervals or poor quality oil, the 4N13 timing chain can stretch prematurely. Regular servicing with Mitsubishi-specified oil prevents this.

Symptoms: Rattling at cold start, rough idle, engine warning light.

The EGR valve on the 1.8 DI-D (Mitsubishi 4N13) cokes up with heavy soot deposits. The intake tract also becomes heavily contaminated. Particularly problematic on short trips. Cleaning or replacement needed every 80,000–100,000 km.

Symptoms: Hesitation and shuddering at mid revs, fault code P0401 (insufficient EGR flow), engine warning light, increased fuel consumption.

The diesel particulate filter on the 1.8 DI-D 4N13 clogs under frequent short-trip use, as the engine rarely reaches the temperature needed for a full regeneration. PSA variants (C4 Aircross, 4008) are similarly affected as the Mitsubishi ASX.

Symptoms: DPF warning light, 'exhaust system defective' message, increased fuel consumption from frequent regeneration attempts, limp mode after complete blockage.

The 4N13 exhaust manifold develops cracks at the EGR pipe connection due to thermal cycling. Combustion gases enter the engine bay, causing frequent DPF regenerations and increased diesel consumption.

Symptoms: Combustion smell in the cabin, more frequent DPF regeneration cycles, diesel mixing into oil, power drop, increased fuel consumption.

Injector seals on the 1.8 DI-D 4N13 fail under thermal stress and combustion pressure spikes. Combustion gases and fuel enter the engine oil, raising the oil level and degrading lubrication.

Symptoms: Rising oil level (oil smells of diesel), ticking noise from the cylinder head, visible oil film around injectors. Diagnosed by leak-off measurement.