Avance à l'injection erronée

Fuel injected at the wrong moment relative to the piston, either through a timing error in the drive or through the module commanding a timing it cannot verify. On a modern engine timing is calculated rather than set, so this is usually the module acting on a wrong reference rather than anybody having mistimed anything.

A stretched timing chain or a slipped belt is the mechanical version, and it moves the camshaft's relationship to the crankshaft so that every calculation based on it is offset. The signature is a correlation code between crankshaft and camshaft alongside the injection fault — the module is telling you its two references disagree.

The consequences are worth understanding because they are visible. Injection too early raises peak pressure and produces a harsh knock and high oxides of nitrogen; too late leaves fuel burning into the exhaust, which shows as smoke, poor economy and rising exhaust temperatures — and on a filter-equipped engine, unnecessary regenerations. Verify the mechanical timing marks before adjusting anything electronic, since a module cannot compensate for a chain that has jumped a tooth.