Code Definition

P1266 — Cylinder #6 High To Low Side Short

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Generic

About P1266

P1266 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1266 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; a signal or supply voltage lower than the expected operating range; and a signal or supply voltage higher than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1266 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Powertrain Control Module (PCM) operates each fuel injector using a high side driver for voltage supply and a low side driver for the ground path. DTC P1266 sets when the PCM detects a short between the high side and low side of the cylinder 6 injector circuit, indicating an unintended low resistance path that permits current flow when there should be none. To protect its output stage the PCM may disable the affected injector driver, and where injectors share a driver bank the fault can affect neighbouring cylinders as well. The driver typically notices a cylinder 6 misfire, rough idle, re...

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