Faulty cylinder 5 injector or injector solenoid with an internal short; Damaged, chafed or shorted wiring between the control unit and the cylinder 5 injector; Corroded, loose or contaminated injector or harness connector, including the connector under the valve cover where fitted; Fault in the injector driver circuit of the injector control module or engine control unit; Coolant, oil or moisture getting into the injector harness or connector; Low or unstable supply voltage to the injector driver circuits.

P1265

Cylinder #5 High To Low Side Short.

Ford
Powertrain
Manufacturer code
High severity

How this code is built

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

What it means

P1265 on a Ford means the engine control system has detected a short between the high side and low side of the cylinder 5 fuel injector circuit. The control unit monitors injector driver current and voltage, and set the code because the readings did not match a healthy injector circuit. The exact layout depends on the engine. It is most commonly seen on diesel engines with solenoid-controlled injectors, so confirm the injector system for your model and year.

Symptoms

Engine misfire or rough running, especially at idle
Loss of power or poor acceleration
Hard starting or no start
Excessive exhaust smoke or a strong fuel smell
Engine warning light on
Engine running on fewer cylinders or stalling

Possible causes

Faulty cylinder 5 injector or injector solenoid with an internal shortlikely
Damaged, chafed or shorted wiring between the control unit and the cylinder 5 injectorlikely
Corroded, loose or contaminated injector or harness connector, including the connector under the valve cover where fittedpossible
Fault in the injector driver circuit of the injector control module or engine control unitpossible
Coolant, oil or moisture getting into the injector harness or connectorpossible
Low or unstable supply voltage to the injector driver circuitsrare

How to diagnose

Read all stored and pending codes and record the freeze frame data, noting any other injector or misfire codes
Check battery condition and charging voltage, as low voltage can upset injector driver circuits
Visually inspect the cylinder 5 injector wiring and connectors for chafing, heat damage, oil contamination, corrosion or bent pins
Check the engine bay and under-valve-cover harness for damage from earlier repairs
With the harness disconnected, measure the cylinder 5 injector coil resistance and compare with the manufacturer specification for your engine
Test the harness wires for short to ground, short to voltage and short between wires, using the wiring diagram for your model
Compare cylinder 5 against the other cylinders using live data or a cylinder balance test if the vehicle supports it
If the injector and wiring test good, check the driver module power, grounds and output signals before suspecting the control unit

How to fix

Replace the cylinder 5 injector if its coil resistance or insulation test is out of specification
Repair or replace damaged injector wiring, using proper sealed repairs and following the original routing
Clean or replace corroded or damaged connectors and terminals, and fix the source of any moisture or oil ingress
Repair or replace the injector control module or engine control unit only after the injector and wiring are proven good
Correct battery, charging or earth faults, then clear the code and road test to confirm it does not return

Can I keep driving?

High severity

Avoid driving until the fault is diagnosed, as a shorted injector circuit can cause misfires, stalling or damage to the driver circuit. If it must be moved, keep it to a short, gentle trip.

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