AGR engine faults.

The internal springs of the flywheel tire, and the two discs knock against each other. The signs are a rattling or knocking from the bellhousing at idle and when releasing the clutch pedal, and vibration through the floor. If the clutch slips without a burnt smell, that also points to the flywheel. It is worth replacing in time: a disintegrated flywheel can destroy the bellhousing too. At a clutch replacement the two go together anyway.

The G62 sensor tells the engine control unit how hot the coolant is. If it is faulty, the control unit thinks a warm engine is cold, and runs it rich: hard warm or cold starting, a rough idle, markedly increased fuel consumption, and a dash temperature gauge that jumps around or never reaches its usual reading. The part is cheap and can be replaced in half an hour: the trouble is that many people do not recognise it and replace an injector or a lambda sensor instead. If the fault persists, the rich mixture can destroy the catalytic converter too.