Faulty cylinder 6 fuel injector with an internal winding short; Chafed or damaged wiring between the injector and the powertrain control module, with the high and low side wires shorting together; Corroded, damaged or contaminated injector connector or harness connector terminals; Water ingress or heat damage in the engine harness near cylinder 6; Faulty injector driver inside the powertrain control module; Short in the wiring to another component sharing the same circuit, depending on model and engine.

P1266

Cylinder 6 High To Low Side Short.

Lincoln
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
2: AreaFuel and air metering (injector circuit)
66: FaultThe specific fault in that area

What it means

P1266 on a Lincoln means the powertrain control module has detected a short between the high side and low side of the cylinder 6 fuel injector circuit. This is a fault in the injector driver circuit, not a fuel or ignition fault in itself. The module saw a drive-circuit voltage or current that did not match what it expected when it commanded that injector.

Symptoms

Engine misfire or rough running, mainly on cylinder 6
Malfunction indicator lamp on
Noticeable loss of power or hesitation
Rough idle or hard starting
Poor fuel economy
Engine may run in a reduced-output or protective strategy

Possible causes

Faulty cylinder 6 fuel injector with an internal winding shortlikely
Chafed or damaged wiring between the injector and the powertrain control module, with the high and low side wires shorting togetherlikely
Corroded, damaged or contaminated injector connector or harness connector terminalspossible
Water ingress or heat damage in the engine harness near cylinder 6possible
Faulty injector driver inside the powertrain control modulerare
Short in the wiring to another component sharing the same circuit, depending on model and enginerare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine load, temperature and speed when the fault set
Check for other injector or misfire codes to see whether the fault is isolated to cylinder 6
Visually inspect the cylinder 6 injector connector and nearby harness for chafing, heat damage, corrosion and bent or pushed-back pins
Listen to or feel each injector with the engine running to compare cylinder 6 against the others
With the injector unplugged, measure its winding resistance and compare with the manufacturer specification for the engine
Check the injector harness wires for shorts to each other, to ground and to supply with the battery disconnected and the module connector released, following the wiring diagram for the model
Swap the cylinder 6 injector with another cylinder if the design allows and see whether the fault follows it
Only after the injector and wiring are proven good, check the module connector and driver circuit as per the manufacturer procedure

How to fix

Replace the cylinder 6 fuel injector if its resistance or operation is out of specification
Repair or replace the damaged section of harness, using proper soldered and sealed repairs
Clean or replace corroded or damaged connector terminals and secure the connector properly
Re-route and secure the harness away from heat and sharp edges
Repair or replace the powertrain control module only if the driver fault is confirmed after all wiring and the injector are cleared, and update the software if the manufacturer requires it

Can I keep driving?

Medium severity

The car can usually be driven short distances to a workshop, but a misfire or injector fault can damage the catalytic converter and may worsen. Avoid heavy loads and long journeys, and stop if the engine runs very roughly or the warning lamp flashes.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.