Jeep

Renegade and Compass diesel, shared with the FCA group. EGR and DPF are the classic checkpoints in city driving.

Renegade, Compass and Cherokee petrol. The MultiAir variable valve timing can trigger timing correlation codes with worn oil.

The solid V6 of the Grand Cherokee and Wrangler. Generally durable, but at high mileage the catalysts and knock sensors start to show their age.