P0263 on Toyota: causes and affected engines

1.4 HDi (1 fault), 1.4 D-4D (1 fault), 2.0/2.2 D-4D (1 fault), 1.2 Turbo (1 fault) and 1.6 Dual VVT-i (1 fault). Each fault has its own page with the affected years and versions, the symptoms and the repair cost.

Cylinder 1 contribution/balance. The ECU has detected that cylinder 1 is performing worse than the others: for the engine to run well, all cylinders must contribute similar power. According to TaT, it detects this by monitoring variations in crankshaft speed. AutoDTCs, on its P0266 page (which describes the same mechanism for cylinder 2), explains that crankshaft acceleration is measured during each cylinder's stroke and that the code is set when that cylinder's contribution falls outside the calibrated parameters. It is a generic OBD-II code: it means the same on a Toyota as on any other make.^{[1][2][3][4][5]}

Garage soon. The sources agree that it must be repaired soon, without being an emergency. Autodoc Club allows short trips but does not recommend it, because a faulty injector can damage the engine and the catalytic converter. AutoDTCs classes it as moderate severity and says it normally does not leave you stranded; on its P0266 page it adds that it is not an immediate safety risk, but that a weak cylinder means loss of power and vibration, and that driving for a long time can worsen mechanical damage and consumption. CarParts.com does not state a severity.^[1][4][5]